Difference between a butter and a lesser?

[The Serpent Merchant]

To me the difference between a Butter and a Lesser is the exact same as the difference between a NERD Lemon Line Pastel, and a Graziani Line Pastel. both are pastels but look significantly different:

Lemon Pastel:



Graziani Pastel:



I would be willing to argue the point that the difference between lessors and butters is even less than the difference between the Lemon Pastel and the Graziane Pastel, but they are considered the same morph.