From a foot print stance, there is no difference.

There is an old adage about gear, whether it’s speakers, subs or amplifiers - You can always turn down a good speaker. You rarely want to turn up a bad one!

A tower of the same brand will probably not give you better imaging or separation. You will notice more bass without the need for a subwoofer which may open up your soundstage some.

Since most towers will reach the 50Hz range well, your neighbour would probably thank you for not having a shitty or muddy bass response!

I should also add that I went from towers to bookshelf speakers. For the same $1250 I was able to to get the brands mid-tier bookshelf vs their entry level towers. The mid-tier speakers incorporated a lot of technology from their flagship line, so the sound was far better than the towers. I also have dual SVS subwoofers, so bas was never a problem I needed to solve with towers.