What is the difference between a basic membership, standard membership and premium membership? Where can I see this information?

For both the MatchEd Community Membership as well as the Vendor 'Serve' Membership, the standard option is the free option, whereas the premium option provides more functions like 10GB of Personal Saved Resources for the Community Membership and increased serve resource, potential for special transaction fee discount, and data reports on purchases, reviews, and ratings for the Vendor 'Serve' Membership.

For the Group Membership, the basic membership is the free option. The standard option has the additional functions of providing all "Premium" Vendor Serve Options for the Group to Post Serve Resources and Monthly Data Reports to Group Owner. The premium option has everything the standard option has, but with free unlimited members, whereas the basic and standard plans only have up to 250 members. 

All of this information can be found if you navigate to your profile icon in the top right corner, click "My Subscriptions", click "Upgrade", and then a comparison of all the plans can be found.