very simply - one with filter, one without filter (paper filter i mean)
and I'm assuming you're comparing long black from espresso vs filter from v60 yea?

If it's pure espresso vs filter, then espresso is a more intense cup of coffee where all flavors are compacted into roughly 30ml vs being stretched out in a 240ml filter brew
Kinda like drinking whisky by shots or diluted with ice/water - stronger vs spreading out flavors

The lack of filter in espresso brewing will give you more oils/dissolved solids in the cup so a higher perception of tactile - mouthfeel, finish, body. Also a little more bitter/gritty because of sediments going through

But it is this intense shot that makes it mixable with milk and other stuffs without getting drowned out (again, similiar to a shot of alcohol)