在表示「開始」的意思時，begin 和 start 為同義詞，可當及物或不及物動詞用，且兩者皆可後接不定詞和動名詞，但 begin 比 start 來得正式。Begin 是個不規則動詞，過去式和過去分詞分別為 began 和 begun。例如：
- Mandy has just begun learning English. (曼蒂剛開始學英文)
- After waiting for about an hour Phoebe was beginning to get angry. (等了大約一小時之後，菲比開始生氣了)
- We started building the house in June. (我們六月份動工興建這棟房子)
- We’ll be starting (the meeting) at 10 a.m. (我們將在上午十點開始 (開會))
Start 亦有「創辦，開辦；(企業或其他機構) 開業，開始營運」的意思 (與 start up 同義)，但 begin 則無這樣的意思。例如：
- Marlon started his own travel agency. (馬龍創辦了自己的旅行社) (正)
Marlon began his own travel agency. (誤) - A new restaurant has started up in our community and it’s been going really well. (我們社區有一家新餐館開業，生意真的很好) (正)
A new restaurant has begun in our community and it’s been going really well. (誤)
Start 還有另一項意思也是 begin 所沒有的，那就是「(機器) 開動，啟動」。例如：
- The car won’t start. (車子發不動) (正)
The car won’t begin. (誤) - I’m having trouble starting the printer. (我的印表機無法啟動) (正)
I’m having trouble beginning the printer. (誤) - Press this button to start the computer. (按這個鈕來啟動電腦) (正)
Press this button to begin the computer. (誤)
其他相關說明請參見「Begin, start, commence (vv.)」這篇文章