suppose 和guess有什么区别?

suppose常指根据一些证据而得出的推断，强调暂时性，可接不定式（特别是to be）、介词短语、形容词等的复合结构，接从句等，作“假定，猜想”等解。如：
We all supposed him to be an actor．我们都以为他是个演员。
Let’s suppose he is right． 让我们假定他是对的。

guess表达说话人在缺乏了解和证据时所陈述的见解，其后可接名词、复合宾语、从句。如：
I should guess the old woman to be about sixty．我猜这位老太太六十岁上下。
Guess how much it is worth．猜猜看这东西值多少钱。

Suppose" used to say you think something is true, although you are uncertain about it.

"Guess" used to say that you think something is true or likely, although you are not sure.

Actually, as in spoken English, they are the same, they can be used as synonyms to each other.

参考资料:
LONGMAN Dictionary of Contemporary English

suppose 有一定的依据作出猜测；
guess 完全是主观的猜测。