Qlik Sense desktop and Qlik Sense Enterprise are providing you with the same functionalities in terms of:
building data model
using extensions and building extensions and mushups
The biggest difference is that Qlik Sense Enterprise will most likely be setup on more powerfull server which:
will most likely have more RAM (64 GB or maybe 128 GB, 256 GB RAM)
will have more powerfull CPU
will be able therefore handle not couple o milions records but couple hundred records / multiple applications
will have possibility of governing an access to application like:
secction access - access to records related to user
AD user name / group name etc - based on user Id each person can only see applications build for them
Enterprise version will have automated data reload capabilities
can be setup as a internal solution (within domain network) or exposed to internet so you could access it from your phone while sitting in taxi
and many many more....
possibility of contribution in development etc
If you are looking for tool to play with and have something to help you do your analysis only on your own computer go for Desktop if you are trying implement solution for whole company - go for Enterprise - entry cost is relatively low!
Contact your Qlik reps or Partner from your area - they will be happy to talk you throug it