I've been instructed to backup my wallet's wallet.dat file.
However, in my wallet software (Multibit), I don't see a backup option other than "Export Private Keys", which saves a .key file.

What is the difference between copying the wallet.dat file and creating a ".key" file using the Export option?

I've been instructed to backup my wallet's wallet.dat file.
However, in my wallet software (Multibit), I don't see a backup option other than "Export Private Keys", which saves a .key file.

What is the difference between copying the wallet.dat file and creating a ".key" file using the Export option?