Sky Tran, there is no difference in meaning. "I will go to the store" and "I will be going to the store" mean essentially the same thing. If you say "I am going" it is present tense. "will" implies future tense. Will is a word with several meanings. If you look it up in the dictionary, you will see several meanings. The most common meaning is for this future tense.

They are both used for indicating the future, however the difference is easy to find by searching "difference will going to". This is a very common question, and plenty has already been written about the differences between them. If you have any English textbooks, they will be able to show the difference as well.