Template tag to differentiate between posts/pages?

Before trying to cook something together myself, I wanted to know if such a tag is already in WP? I’m currently on the 9/26 daily, and flipping through both wp-includes/template-functions-* and codex isn’t turning anything up.
The reason I want this is so that I can configure my template to show posts differently from static pages, but I’m not finding a tag to make this possible.
Wanted to check here before posting a request on the mosquito.