wpf - Prism v4: Unity or MEF? -

i downloaded prism v4 , ran installer. went directory , ran 2 following batch files:

• desktop - open modularity mef quickstart.bat
• desktop - open modularity unity quickstart.bat

when compile these applications, don't see real difference. i've searched mef vs unity , i've found pros/cons, nothing states whether 1 "better" (and know subjective) use in prism. guess perhaps if list requirements can point me correct technologies use (even if it's not prism 4).

• the application written in wpf (not silverlight).
• the main application extremely thin.
• the main application use web service build menu of "apps/modules" person has access to.
• the "apps/modules" contained in other managed libraries.
• the main application gets views , viewmodels reflecting these dlls.
• the main application should feed in services logging, etc. these "apps/modules".

for example:

a basic user might have options of:

• viewonly address record

all items address related within address.dll.

an advanced user might have options of:

• new address record
• open address record (update/delete)
• manage users

all items address related within address.dll.
items manage related within admin.dll.

app should not reference either of these dlls, plan reflect them if there 100 different modules , user has access 2 of them, 2 of them downloaded , used. whereas user has access 10 of them gets 10.

i've solved downloading dll via webservice. :)

none "better": different things.

imo choice should driven requirements. based on requirements posted here suggest use mef, because have modules contained in dlls , main app unaware of modules load. tasks reason why mef exists.

anyway use them both: mef modularity , unity take advantages of dependency injection (testability, reusability, ...)