这两个动词均有“庆祝，祝贺”之意。
celebrate : 通常指举行盛大隆重的仪式庆祝或纪念有意义的日子或某件事情，多暗示节日般的欢乐场面。
- We always celebrate our wedding anniversary by going out to dinner.
每年的结婚纪念日我们都出去吃饭庆祝。 - If this plan works, we'll celebrate in style (= in a special way).
要是这个计划奏效，我们就隆重地庆贺一下。
congratulate : 指对他人祝贺为目的，希望他人幸福或走运。
- I was just congratulating Ceri on winning/on having won her race.
我那时正在祝贺凯里赛跑获胜。 - I congratulated them all on their results.
我为他们取得的成就向他们所有人表示祝贺。 - The authors are to be congratulated on producing such a clear and authoritative work.
向创作出这样一部具有权威性又清晰易懂的作品的作者们祝贺。 - She congratulated him on the birth of his son.
她祝贺他喜得贵子。
