I have BROUGHT you a present that I BOUGHT yesterday. Here it is! Brought = past simple/past participle of the verb TO BRING. Bought = past simple/past participle of the verb TO BUY. BRING > BROUGHT BUY > BOUGHT Lovely weird English spelling!

hi, 'brought' is the past tense of bring (bring, bringing, and then brought) and bought is the past tense of 'buy' (buy, buying, and bought)