Is there any word in Irish that is the same in English or is it all a different language? I have heard Irish people speak to each other and they speak English.
Irish is a Celtic language and English is a Germanic language. Irish has English loan words and English has Celtic loan words. For example cavalry comes from Celtic languages. But basically it is a different language. Both, Celtic and Germanic are two different branches of the Indo European languages.
Due to Irish history and British occupation, Ireland almost lost its language. British language politics was to take the Irish their language (and not replace it well). You could say Irish is being revived. Not everyone in Ireland speaks Irish but more and more people speak it on daily basis. Many Irish people learn Irish as foreign language - so Duolingo fills a great place also for the Irish. Irish has been influenced by North Germanic languages as well. Ireland was conquered by the Vikings like England. They also made Dublin its capital.
The difference being that "cat" has been part of Irish for over a thousand years, yet it hasn't been modified or changed, even though all of the other domestic animals around us use very different words in English and Irish. (I was going to quote from the ninth century poem to Pangur Bán, but it looks as though Pangur Bán was never actually referred to as a cat). There are lots of words in both languages that share a common root, but are quite different now, and it didn't sound like they were the kid of words that EllaWeber was looking for anyway.
Banana is more obviously a modern loan word, but it usefully highlights the fact that such borrowings often produce similar words, but not always the same word in both languages, so you don't need to do a lot of study to guess that "tea" and "tae" might be related, or "coffee" and "caife", but they wouldn't fit EllaWebers request for words that are the same in both languages.