Hey @terrylovejoy, thank you for the support! It's always good to see you around, thanks for dropping by my blog. The Hammer Projection is an equal-area projection that utilizes the same elliptical shape as the Mollweide Projection which is why the are so similar to each other.

The Hammer-Aitoff is an equal-area projection as well, however it stems from the Lambert Azimuthal equal-area Projection by modifying some of its geometric properties. It does bare resemblance to the Mollweide Projection in certain cases for sure though!

Stay awesome!