Beach has the long e sound in English Bitch has the short i sound. Forvo.com is a useful site for hearing how words are pronounced with different accents, in American and British English

The pronunciation of beach is long as an "beeeeeach" where as the other word is pronounced short. Hope that helps! Italians tend to mispronounce this word as well.

"Beach" in American English is here. I think for this word, in British english it's the same or very similar.