The difference is that the center placement can include being inside cabinets. I didn’t think I needed to be that specific. My bad.Perhaps you have 80hz crossover, some other people might not. As I noted, Arendal has addressed the size disparity with their monster 1528 center probably best that it could be done. But also, good luck tilting that center.
@Lsc - same could be said for the towers as "placement could vary". In theory you LCR speakers should be the same, so in my book it translates into either ported or sealed. However, the world will obviously not end if the ideal state is not achieved.