Difference Between TRV Less than 6 Months, and TRV More than 6 months.

[mtlexplorer]

TRV - Less than 6 months ( Multiple Entry - 10 Years )
TRV - More than 6 months ( Multiple Entry - 10 Years )

I created a personal reference code for both these options and noticed that for the TRV with more than 6 months option, they need
proof that the Visitor will go back after a certain period. (Flight Itenirary).
Also, they are requesting Medical Exam Report IMM 1017B (This I already have as I included my Family as Accompanying on PR app)
The other things they ask are proof of funds, Invitation Letter, Proof of Relationship etc.

However, they do not ask the above just mentioned for TRV - Less than 6 months Category.

Can you advice if both TRV categories are extendable in any case.

I feel that the TRV Less than 6 months has less paperwork and proofing required.
(on the other hand)
the TRV More than 6 months allows for lengthier period of stay; but there should be proof of leaving the country at some point.