Pictures at the same size

I have two pictures of the same person taken in two differents days. This two pictures are the face of the person and it was tried to be taken in the same scale, however due to the difficulty of the this, this is a difference in size.
my question: is there any way to put both of them at the same size ?
thank you

Hello Carmen -

This is called “image registration” (and is a well-studied topic in
image processing).

Fiji / ImageJ ships with a number of image-registration plugins.
Look at:

Plugins > Registration

You might start with the SIFT-registration plugin:

Plugins > Registration > Linear Stack Alignment with SIFT

Thanks, mm