The 5090 laptop series kind of proves that the architecture improvements are minor for this generation. Both laptop chips - 4090 and 5090 use the 4080 and 5080 dies respectively. Both are capped at 175W power draw which is under the limit for their desktop variants i.e. both laptop GPUs are performing under their capabilities due to power limitations.
The benchmarks I have seen seem to put the 5090 5-10% of the 4090 which is what the performance uplift due to architecture improvements indicate, while their desktop counterparts can draw more power for a slightly larger performance uplift over the previous gen.
While Im not a fan of the MFG on the desktop, I kind of think its nice to have on a laptop where a smaller screen and inability to upgrade makes frame gen more viable.