[yorby]

This is false for comments... it is true for posts however.

Also, reddit once said that they only keep the latest version of a comment in their database (not sure if it is still true though).... so if you want to really delete a comment from reddit, you have to edit it to some random text and then delete it.

[Buge]

It's false for posts as well, if it's a text post. The text of the post is deleted.

If it's a link post, then it isn't deleted.