What's the difference between the following sentences: "he looks happy." "he looks like he's happy." "he seems happy."

The first and third sentences are about the same, both simple sentences; the only difference is the use of different verbs, "looks" and "seems." They give the sentence slight changes in meaning, but the structure is identical: subject, verb, predicate adjective.

The second sentence is a complex sentence with an error in it. It's complex because it has two clauses ("he looks" and "like he's happy"), one independent and one dependent. The error is that "like" is used incorrectly. That word is not a subordinating conjunction, which is what is needed here. Change "like" to "as if," and it'll be correct.
http://www.answers.com/like
(Scroll down to see all the different CORRECT ways "like" can be used; at the bottom of the list, you'll see "conj. Usage Problem" which means it's not correctly used as a conjunction.

If you have further questions about these sentences, please repost.

=)

thank you so much!!! you really helped!

You're very welcome!

=)

The difference between these sentences lies in the different ways they express someone's apparent happiness. Allow me to break it down for you:

1. "He looks happy."
In this sentence, the word "looks" suggests that the speaker is making an observation based on the person's appearance. It implies that the person's facial expressions, body language, or overall demeanor indicate happiness. This sentence directly states the person's emotional state.

2. "He looks like he's happy."
Similar to the first sentence, this sentence also uses the word "looks" to indicate observation. However, the addition of "like" introduces a comparison or resemblance. It implies that the person's appearance is similar to what one would expect from someone who is happy. This sentence suggests that the speaker is not entirely certain about the person's emotional state but is assuming they are happy based on their appearance.

3. "He seems happy."
In this sentence, the word "seems" implies that the speaker is making an inference or a subjective judgment about the person's emotional state. It suggests that the person's behavior, actions, or other non-verbal cues lead to the conclusion that they might be happy. This sentence is more speculative or tentative compared to the previous two, as it acknowledges that the speaker is interpreting the person's emotions rather than making a definitive statement.

To summarize, while all three sentences describe someone's apparent happiness, they differ in the level of certainty, inference, and comparison used to convey the observation.