They have totally different semantics.
AddRange modifies the list by adding the other items to it.
Concat returns a new sequence containing the list and the other items, without modifying the list.
Choose whichever one has the semantics you want.
They have totally different semantics.
AddRange modifies the list by adding the other items to it.
Concat returns a new sequence containing the list and the other items, without modifying the list.
Choose whichever one has the semantics you want.