Students can use both to share learning materials and updates about class activities to the community. But for the followings tasks I would prefer the use of Sites:
- Digital Portfolios showcasing personal learning
- Group projects where students create their own pages and share it with others
- Class announcements
Blogs would be better on the following tasks:
- Encourage peer critique by allowing students to post comments and feedback on each others blog.
- To cover a wide variety of articles.
- Keep parents updated about their kids learning