People who are interested in pursuing a career in public health often face a question: Should they get a graduate certificate in public health or go all in and pursue a master’s degree in public health (MPH)? That decision often depends on a student’s goals, as both academic pursuits attract people who wish to make a difference in the welfare of others, according to Mark Williams, the M. Joycelyn Elders Professor of Health Promotion and Disease Prevention Dean at the University of Arkansas for Medical Sciences’ Fay W. Boozman College of Public Health.

“It’s science that investigates how to best provide public health interventions, how to track diseases within populations, and all of the methodologies that go along with doing that,” says Williams of the public health field.

If you’re trying to decide whether a certificate program or a master’s degree program in public health is right, here’s what two experts told Fortune.

What is the difference between an MPH and a graduate certificate in public health?

Public health is dedicated to the science of prolonging life, preventing disease, and promoting health for society at large. A common way for people to enter this field is by obtaining an MPH degree.

“It gives them professional skills to specialize in a particular area that they want to work,” says George Gray, associate dean of MPH programs and program director at George Washington University’s Milken Institute School of Public Health. The school landed the No. 1 spot on Fortune’s first-ever ranking of the best online MPH programs. “We are making students who can go out and make a difference on the front lines of public health.”

Often, Williams says, someone pursuing an MPH works in some sort of preventative health practice—meaning they focus on keeping patients healthy instead of treating them only when they are sick or injured—or is a person who wants to become a public health scientist.

Students who pursue a graduate certification in public health, on the other hand, tend to be more seasoned in their careers than those seeking an MPH, Gray says. 

“The certificate often attracts people who are perhaps a little more advanced in their careers,” Gray says. “They may be advanced in a parallel career, or a career that might touch on public health, or might have made them aware of public health, but it wasn’t something that they were thinking of when they started out.”

What’s more, a graduate certificate program—which is 15 credits at George Washington, compared with 45 credits for the MPH program—may be a way for some people to test the waters to see if the field of public health is right for them. 

“It makes up most of our core courses, which are the base courses that all MPH students have to have,” says Gray of GWU’s graduate certification. “It gives students a great exposure to the range of topic issues and tools that are used and studied in public health.”

Finally, the scope of the two options is inherently different. Williams compares the certification to an introduction to public health, whereas the MPH goes into more advanced coursework.

“For someone coming out of college who wants to look at disease prevention and is interested in health, I would highly recommend that they get an MPH,” Williams says. In contrast, he recommends a certification to a working professional who has another health degree because of the time constraints caused by already being employed.

Time and expense—how do an MPH and public health graduate certificate compare?

When it comes to time and expense, a public health certification is something like a mini-MPH program. “A certification is about half the time of a master’s degree,” Williams says. “It’s half the time, half the expense.”

Gray lauds the certificate for imparting a base knowledge in public health that can be done at a student’s own pace. One current student in GWU’s program, Gray notes, is a physician in an emergency room who is taking one course each term. Other students with more flexible schedules knock out the certificate in two terms.

“Our program is flexible,” Gray says. “If a student successfully completes the certificate within good academic standing, they are automatically accepted into our MPH program.”

Not only are GWU’s certification courses directly transferable to its master’s degree program, but the certification courses are offered at a discount per credit hour compared with the school’s MPH. And generally speaking, students who obtain a certificate often continue in their schooling to pursue a master’s degree.

“That probably happens about half of the time,” Williams says. “After and during COVID, we had a lot of people that got a certification and then wanted more expertise in infectious diseases, in particular, and how to study those and understand them. They went on to get an MPH with a concentration in epidemiology.”

What is the benefit of having an MPH or a public health graduate certificate?

Obtaining either an MPH or a graduate certificate in public health can have career and salary benefits, both Gray and Williams agree. 

A graduate certificate “tells employers and others that [certificate holders] have this exposure and experience with a broad range of topics in public health,” Gray notes. The MPH, he adds, allows graduates to specialize in an area of public health they want to work in, and get “a real leg up in the employment world.”

People who pursue an MPH generally wish to stay within their current organization, but “want to gain some sort of insight and develop some expertise in public health so they can move up,” Williams says. “A physician who has clinical training, but not public health training, and is working in a health department, oftentimes will get an MPH or a public health certificate, depending on how much time they have,” he adds.

Check out all of Fortune’s rankings of degree programs, and learn more about specific career paths.