A blog is discussion or informational website often with diary-style entries.
A wiki is a collection of user-created and edited interlinked webpages.
This quiz from the University of Illinois will help you narrow down your choice of blogging platforms.
The most well-known Wiki is Wikipedia. You can create your own using one of these tools. The one you choose will depend on your level of coding expertise and your purpose for creating it.
Some wiki creators are:
You can also create your own Wikipedia page. You will have to register as a Wikipedia editor.