YES, NO, Maybe so!!!!
This is so dependent on what you are comparing,...
IN GENERAL,...
7200 rpm drives will be overall faster in overall performance
for laptops,... overall 5400 rpm drives will be overall better "in terms of battery hours per full charge"
Now,... why are you replacing the HardDrive should be asked,...?
Performance? Then get a 7200 rpm drive after researching the drives in that category and space you are looking for
Battery life? The get a 5400 rpm drive after seeing which are good performers while giving you extra minutes
Space? Well you can upgrade space at either level quite easily,...
Do you have an issue with your current Harddrive? the only reason to really upgrade would be space issues or harddrive not working,... if you replace just the harddrive for performance,... yes there is a bit to be had,... but not at all when you consider bang for the buck,... if you are looking at overall performance upgrade you need to look at RAM or possibly a new laptop,...