Despite my respect for the other answers, I have a contrarian opinion and I say there's no difference at all between the two. Notice both answers say "very similar" and "almost identical." I say they're identical. This question is a good example of being able to express the exact same idea using different sentence structures in the English language.

"To be or not to be" from William Shakespeare's play "Hamlet". "She seems to be happy" or She seems to be unhappy? "She seems happy" is more matter of fact.

They are almost identical. "She seems happy" is a judgement made after a very quick assessment. "She seems to be happy" is probably said after a slightly longer assessment of the person with a view to assessing her future happiness in the situation she is in.

They are VERY similar actually. In fact, the only difference i can think of is that "she seems happy" might mean 'right at that time' but "she seems to be happy" might mean that she is happy in many ways or is always happy.

Whose answer is ok, I wonder?