You could say that if you Teach English in another country you are teaching English in a different environment
. It can also be said if you are teaching English in Los Angeles instead of the city you were born in like Des Moines, IA that you are teaching English in a different environment. For certain, both qualify as different environments than the original one.
If you are going to teach school in any subject in the United States then you will have to be certified in the state where you want to teach. To do this you will have met various education requirements already. Then you will have to pass their teachers certification program. Depending on whether you want to teach elementary school or junior high or high school will dictate which education requirements you will have to meet and what certification tests you will have to pass. Then you will have to apply for the jobs you are interested in. To teach English you also have to comply with these same requirements.
For the most part where ever you are hired to teach in the United States, English will be the first language of most of your fellow teachers. You will also know the general way to conduct business and get various things accomplished. You will understand the social and political conventions. You will also understand most all of the driving rules and be able to easily obtain a drivers license in whatever state you have chosen to live. Other than different brand names you will be familiar with most of the foods at the markets.
If you are going to teach English in another country you may have completely different requirements to meet. But you will also be teaching in a very different environment. They may speak a different language and so you will have to know some of the words to get by even for the first week. If you are going to live there for a year you may have to get electricity or the cable company or internet connections in your name. You may not be at all familiar with the bureaucracy that may be involved to accomplish these tasks. There may be entirely different foods at the supermarket. Such things as asking for directions may present challenges. You may have to learn a new currency. Certainly you will have to learn how to navigate the political and cultural landscape.
Social conventions may be very different than where you lived before. If you are in the United Kingdom, you will have to learn to look a different direction when you cross the street. There may be many other new things to learn in order to survive living in the new country.
You certainly should look at it as an opportunity to learn about a different culture and history than you are familiar with. You may acquire new tastes for different foods. You certainly will expand your thinking and outlook on life. You may find that you have changed.