She's at home.
Are there any differences in meaning?
If you mean that she is in her house, flat, or apartment, you can say either "She is home" or "She is at home", without any difference in meaning.
The only difference is syntactic. When you say "She's at home", you are using the word home as a noun. On the other hand, when you say "She's home", you are using home as an adverb, which means at home.