I am not great at describing tomato leaves yet. I can see these two are clearly different, but how would you describe the differences?
These two plants were meant to be the same variety

The one in the right almost looks like the leaf of a determinate variety, while the one on the left looks like it could possibly belong to an indeterminate and also have heterozygous alleles for "Regular" and "Potato" leaves.

*All speculation*
Did you have a determinate variety crossed with an indeterminate potato leaf variety?

"Lightly serrated" on the left and "Deeply serrated" on the right? I've forgotten these botanical terms, but it sure is difficult to describe leaf differences in different tomatoes. They are pretty irregular, leaf to leaf, in the RL's. Potato leaf is more consistent/less varied.

Found this while searching for something completely unrelated. Thought I'd share

https://books.google.com/books?id=CyAnA ... es&f=false

Leaf morphology is very interesting topic that I would like to understand better too. The topic is surprisingly complex and messy at least if one starts from the scientific literature. It is surpringly difficult to describe what exactly is different in leaves (or growing habbits) when you see a speciment which does not quite match the normal wild type. It seems that it is not enough to look how smooth or how deep cuts the leaf edges have but one shoud also check the leaflet structures and their organization.

I also googled a little and was surprised that there are tomato leaves with three leaflets only (i.e. terminal and one pair) or that potato leaves are completely missing the smaller leaflets between the primary leaflet pairs, for example. And one article claimed that regular leave tomatoes should have always three pairs of primary leaflets but potato leaves only two pairs. I never saw this in my plants.

Here is a nice summary of tomato leaf types which is not complete but probably enough for most of us: https://www.worldtomatosociety.com/glossary/leaf-type/

[mention]Pippin[/mention] , that was presented very well. Enjoyable read.