They cannot have the same geometry.
Sure they can, in theory, you could make a bike with 100mm travel but the geometry of a 150mm bike it’s just that nobody wants to, so nobody has done it…
TBH though It’s all a bit too hyperthetical really, I suppose the simple answer is that of course they would feel different the suspension reaction to rider input and terrain will always vary with more or less travel available…
Real world wise you’d tend to buy a bike where the geometry/suspension fits your requirements eg; You won’t buy a DH bike when you need an XC whippet, and you won’t buy a 9″ DH bike when you need a trail bike… Or you might, I dunno it’s your choice…
if you really want to make a 150mm bike behave like a 100mm one, take about 50mm off the travel…