I think "Đầy" is "fulfil" or "full" ( water , liquid ) , "đủ" is "enough" . Example : - Ly nước này đầy rồi ( This glass is full of water ) - Mọi việc làm tới đây là đủ rồi . ( Untill now everything is enough ) "Đầy đủ" is popularly used , too . Its same to "full" or "completely . Hope my answer will help somehow . Thank you for reading

Actually, I think : Đầy = Full Đầy đủ = đủ = Enough But there are some differences between "Đầy đủ" and "đủ" + Đầy đủ is kind of formal form of "đủ" . We usually use "đủ" in daily conversation. + Đầy đủ = đủ but sometimes we use "đầy đủ" to emphasize the sentence. Ex: Tôi có đầy đủ những gì anh cần. Tôi có đủ những gì anh cần They have the same meaning but the first sentence is more emphasized. + Finally, it is depend on words you use with and the sentence structure . Some cases we can't use "đủ" but "đầy đủ" and vice versa. Ex: We say "Tôi chỉ cần em là đủ" not "Tôi chỉ cần em là đầy đủ" We can say "Làm bài tập đầy đủ" not "Làm bài tập đủ" , but we can say "Làm đủ bài tập".

cảm ơn xukababuka.

Hello, i think "Đủ" means "Enough, it is a enough number for (doing) something " and "Đầy đủ" means "Full (of) - nothing is missing according to the requirements" For example you say: "Tôi có đủ (tiền) để xây nhà" means "I have enough (money) to build a house" "Tôi có đầy đủ (dụng cụ) để xây nhà" means "I have full of tools to build a house" Or another "Tôi sống đủ" - I have enough to live (but I might need to thing else to make me happier) "Tôi sống đầy đủ" - I have everything I need to live" (and I don't need more) The differences between those are just slightly because in general it all means "enough". I hope you can understand what I've explained. Good luck ;)