Will a MacBook Pro hard drive fit in a iMac 21.5”

Hi

I had an MacBook Pro and I replaced the hard drive in it for a SSD. I kept hold of the HD wich is a 500gb 2.5” SATA disk.

Recently the hard drive on my mums 21.5” iMac (Late 2012) failed and I’ve decided to change it myself, I wanted to use the hard drive I removed from my MacBook Pro, will it fit or is it a different sized enclosure etc?

Thanks in advance

Rob