Hello I'm glad you are interested in industrial engineering. Industrial Engineers work in many industries to design better systems of people, machines, information, and energy - from helping design systems which make different kinds of products (such as makeup, cars, even breakfast cereal!) to helping organize transportation systems (such as airline schedules and truck routes) to making health care systems work more effectively (so it takes less time to be seen by a doctor in an emergency room).
There is a new video out about IE careers - have a look at http://www.youtube.com/watch?v=WMbJuTlajsw
No matter what kind of engineering you want to be, you should take a solid math and science curriculum in high school - in math, take math every year up through pre-calculus or even calculus if it is offered. You should also take science every year - chemistry, physics, earth science - whatever the complete, college-prep science sequence is in your state. All engineering colleges will expect you to have taken math and science throughout high school. If a computer programming course is offered, that can be good experience as well. At 4 year colleges or universities you would choose to be an engineering major (generally) or a specific kind of engineering major (for instance, industrial engineering or electrical engineering). At community or 2 year colleges there is usually an engineering science or engineering prep curriculum that allows you to transfer to 4 year colleges for engineering. (Engineering technology is usually not the same thing). Your high school guidance counselors or the admissions counselors at the colleges can help you pick. It is also easy to find information about majors on college web sites.
You ask if there is a big difference between different kinds of engineering - there are differences in the types of things people work on day to day between different kinds of engineers (say, chemical compared to electrical) - but there are also differences WITHIN the types of engineering. Some civil engineers might design structures such as bridges, while others work to make waste water treatment safer. Some industrial engineers use math to design airline schedules, while others measure the quality of automotive products. The good news is the you do not have to make up your mind about what kind of engineer you want to be right now. Math and science courses are the right preparation for all engineering majors. At most colleges, you can become an engineering student even if you are not sure of what kind of engineering you want to take. The freshman and sometimes sophomore year courses are similar and flexible so you can switch from one engineering major to another easily. Colleges usually offer courses to help introduce freshmen to all kinds of engineering careers - even some you haven't ever heard of - to help students make that decision. If you have any other questions, please let me know.
Sincerely, Ann Bisantz