Amazon and two other American titans are trying to shake up health care by experimenting with their own employees’ coverage. By Chinese standards, they’re behind the curve.

Technology companies like Alibaba and Tencent have made health care a priority for years, and are using China as their laboratory. After testing online medical advice and drug tracking systems, they are now focused on a more advanced tool: artificial intelligence.

Their aggressive push underscores the differences between the health care systems in China and the United States.

Chinese hospitals are overburdened, with just 1.5 doctors for every 1,000 people — barely half the figure in the United States. Along with a rapidly aging population, China also has the largest number of obese children in the world, as well as more diabetes patients than anywhere else.

The companies’ technological push is encouraged by the government. Beijing has said it wants to be a leader in A.I. by 2030 and pledged to take on the United States in the field. While officials have emphasized the use of artificial intelligence in areas like defense and self-driving cars, they have also aggressively promoted its use in health care.

Alibaba and Tencent, which already dominate China’s e-commerce and mobile payments sectors, are at the forefront. Among their goals: building diagnostic tools that will make doctors more efficient.

Amazon and its partners, JPMorgan Chase and Berkshire Hathaway, see technology as a way to provide simplified, affordable medical services. Although the alliance is still in the early stages, it could create online services for medical advice or use its overall heft to negotiate for lower drug prices.

“It’s fair to say that across the board, the Chinese tech companies have all embraced being involved in and being active in the healthcare space, unlike the U.S., where some of them have and some have not,” said Laura Nelson Carney, an Asia-Pacific healthcare analyst at Bernstein Research.

“Few of them have made moves as big as in China,” Ms. Carney said, referring to Alibaba and Tencent’s American rivals.

Those big moves have had varying degrees of success.

In 2014, Alibaba announced a “future hospital” plan intended to make treatment more efficient by allowing patients to consult with doctors online and order drugs via the internet. But two years later, Chinese regulators stopped the sale of over-the-counter drugs on Tmall, Alibaba’s e-commerce website. They also suspended a drug-monitoring system that the company had created. And last year, the search engine company Baidu scrapped its internet healthcare service, which allowed patients to book doctors appointments through an app, in a bid to focus solely on A.I.

But some of the more recent initiatives have made inroads. Last year, Alibaba’s health unit introduced A.I. software that can help interpret CT scans and an A.I. medical lab to help doctors make diagnoses. About a month later, Tencent unveiled Miying, a medical imaging program that helps doctors detect early signs of cancer, in the southwestern region of Guangxi. It is now used in nearly 100 hospitals across China.

Tencent has also invested in WeDoctor Group, which has opened its own take on Alibaba’s “future hospital” in northwestern China. The service allows patients to video chat with doctors and fill their prescriptions online.

Advances in artificial intelligence have already been transformative for China’s overworked doctors.

Dr. Yu Weihong, an ophthalmologist at Peking Union Medical College Hospital, said she used to take up to two days to analyze a patient’s eyes by scrutinizing grainy images before discussing her findings with colleagues and writing up a report. Artificial intelligence software currently being tested by the hospital helps her do all that dramatically faster.

“Now, you don’t even need a minute,” she said.

The software has been developed by VoxelCloud, a start-up has raised about $28.5 million from companies including Tencent and the Silicon Valley venture capital firm Sequoia Capital. It specializes in automated medical image analysis, helping eye doctors like Dr. Yu screen patients for diabetic retinopathy, the leading cause of blindness among China’s working-age population.

There are just 20 eye doctors for every million people here, a third of the proportion in the United States. In April, Beijing announced an ambitious plan for the country’s 110 million diabetics to undergo eye tests.

“It’s impossible for one person to read that many images,” said Dr. Yu.

Ding Xiaowei, whose grandparents were doctors, founded VoxelCloud in 2016, three months after completing his doctorate in computer science at U.C.L.A. The company, which has offices in Los Angeles and the Chinese cities of Shanghai and Suzhou, is awaiting the green light from China’s version of the F.D.A. for five diagnostic tools for CT scans and retina disease.

The sheer size of China’s population — nearly 1.4 billion people who could provide a vast number of images to feed into their systems — provides a potential advantage for the development of artificial intelligence. Also helping: China has fewer concerns about privacy, allowing for easier collection of data that could result in smarter and more efficient A.I. systems. Regulation here isn’t as strict as in the United States, either.

In all, more than 130 companies are applying A.I. in ways that could increase the efficiency of China’s health care system, according to Yiou Intelligence, an industry consultancy based in Beijing. They range from behemoths like Alibaba and Tencent to domestic champions iFlyTek, which invented a robot that passed a Chinese medical licensing exam, and an array of smaller start-ups like Shenzhen's Drugdu.com.

Money is flowing in. As of last August, venture capitalists such as Sequoia and Matrix Partners had invested at least $2.7 billion in such businesses, according to Yiou. Analysts at Bernstein estimated that spending in China’s health tech industry will reach $150 billion by 2020.

Behind this push is a realization that the country’s health care system is in crisis. With no functioning primary care system, patients flock to hospitals in major cities, sometimes camping out overnight just to get treatment for a fever. Doctors are overworked, and reports of stabbings and assaults by frustrated patients and their relatives are not uncommon.

Yunfeng, the personal investment fund of the Alibaba founder Jack Ma, has invested in one company, Yitu, that hopes to address the shortfall of resources. Yitu is working with Zhejiang Provincial People’s Hospital, the best medical facility in eastern Zhejiang province, to develop software that automates the identification of early stages of lung cancer.

While it initially focused on facial recognition, Yitu has branched out into more complex image-recognition challenges, like cancer scans. Lin Chenxi, who left Alibaba to establish the company in 2012, said he hoped to use the technology to ensure equal access to medical treatment across China.

“In China, medical resources are very scarce and unequally distributed so that the top resources are concentrated in provincial capitals,” he said. “With this system, if it can be used at hospitals in rural cities, then it will make the medical experience much better.”

Trying to identify cancer nodes — shifting black-and-white splotches that look something like a Rorschach test — is grueling work, and China’s doctors have far less time and resources than their counterparts in the United States and elsewhere. Gong Xiangyang, the head of the hospital’s radiology department, likened the process to a factory, where burnout and mistakes from overwork can happen.

“We have to deal with a vast amount of medical images every day,” he said. “So we welcome technology if it can relieve the pressure while boosting efficiency and accuracy.”