The above question was bit different then what are you referring to.
Talking about your question, both (MF and CR) are a completely different application.
Consider #memberfactory = 1 course/site (Recurring Payment or One time Payment)
Consider #coachrack = multiple courses/site, in a store like a format (Recurring or Only One-time payment).
The difference between Memberfactory & CoachRack is that MemberFactory is useful if you have only one course and wish to sell it in a membership style by charging your customers a subscription fee.
Where CoachRack is more useful if you have multiple courses and wish to create School and sell from a store like a website.
MemberFactory is to create a standalone Membership site, wherein CoachRack you can create multiple courses and add those courses in School.