When making comparisons they are very similar, but not fully interchangeable. Usually you can identify which you should use by sentence structure. For "like", the sentence structure is usually Verb + "like" + Noun/Pronoun as in "She looks like a teacher." For "as", the structure will usually be "as" + Subject + Verb as in "No one plays football as he does." In American English though, we would usually say "No one plays football like he does." even though the British would probably say this was incorrect. The reason that they are not fully interchangeable though is that "as" could define a formal role or relationship. There is a subtle, but very important, difference between the two sentences "As your wife, I love that shirt." and "Like your wife, I love that shirt." In the first, the speaker IS your wife while in the second, he or she is simply agreeing with your wife. It is a silly example, but the point is that you could create an awkward situation by accidentally speaking as if you were someone's spouse, boss or other significant relationship when you meant to say "like" instead. Your English is great. Keep up the good work!

I really can't understand what your question is - can you please post some example sentences?