Health inequality means that different people in different places have different possibilities when it comes to staying healthy. Some people have better access to things like nutritious food, safe places to exercise, and doctors who can give them good medical care, while other people have the opposite.
Environmental influence is the ways our environment can affect our health. For example, living in a place with lots of pollution can make it harder for people to breathe and stay healthy. Living in areas without healthy, affordable food can make it much harder for people to get enough nutrition. A lack of clean water can lead to people getting sick more often. All of these differences in the environment can lead to health inequality - some people's environment make it much harder for them to stay healthy than other people's.