What is the difference between microdata and microformats?

I have searched quite a bit for this and I am not happy enough with what I have read. I also found these questions here:

Microdata vs. Microformats

What are the advantages of Schema.org's microdata vs Microformats et al?

I have a news/social network site in spanish and wanted to know what would be the best format to implement.

Currently, I have both running. But I want to know if it is better to have only one, if so, which one would best fit my site? Or, can I keep both of them?

I want to target most search engines, not only google.