They are mostly the same, but there are a few differences: 1. "Tanked" means really failed, or did not even come close to succeeding. You can come close to success but still fail, but in that situation you would not say "tanked." 2. "Tanked IT" or "failed IT" is something we would use when talking about a particular, short event that you failed at, like a test or an interview. The "it" refers to the test or the interview. But if you are talking about something that takes a long time -- like trying to build a business -- you could say "I failed at building a successful business" but you would not say "I failed IT."

In English, "tanked" is a slang word for getting drunk, as in, "he got tanked at the party." The word can also be construed as failing, such as, "the movie tanked" - in other words, it was not a success among moviegoers. If you failed a test, for example, you wouldn't say "I tanked it", you would say "I failed it". I hope this helps!