While they may physically fit, it's unlikely they would work very well.
Certainly they won't work at 1333 MHz; at best they'll be clocked down to 1066 MHz.
But the newer model uses PC3 8500 or PC 10600, and the MB will only use PC3 8500 if it's the late 2009/early 2010 model.
Earlier MBs use PC2 and the swap would be very iffy.
Full specification of MB5.1 RAM;
204-pin PC3-8500 (1066 MHz) DDR3 SO-DIMM, non-ECC (non parity), unbuffered.
MBP8.1, 8.2 or 8.3;
204-pin PC3-10600 (1333 MHz) DDR3 SO-DIMM, non-ECC (non parity), unbuffered.
PC3 is the same as DDR3. the number is peak transfer rate (approximated).
Further reading suggests your swap may work, but it's not guaranteed. If you get 3 beeps on start up (or the sleep light flashing in bursts of 3), first check it's correctly seated, but be prepared to swap them back.
If you encounter any instability or kernel panics, change them back.