Hi,

I think their Pinout is different. If possible, I would suggest using 573 cause the layout for PCB will be much more neater than using 373.

And usually (at my country), 74373 is available in LS and 573 is available in HC. Thus, you have to be careful in what you are interfacing cause the input voltage level for HC and LS is different. If this is a problem for you, you can try using 74HCT573 or even use pull up resistors.

Hope it helps !

Best Regards
Andy