The initial comment was only about "plumping up", or in essence fat building.

Both sandwiches have the exact same amount of carbs, two slices of bread. In regards to carbs these sandwiches are identical. Your macros for carbs are the same no matter what.

One sandwich has more meat and more cheese, so more calories worth of fats and proteins. Your macros of proteins and fats are higher in the big sandwich.

And specifically in the context of "plumping up" as OP talked about, your calorie count is higher in the larger sandwich. Macros are for general nutrition and muscle building goals. Weight gain/loss only cares about calories.

Equivalent carbs. Higher calories. The bigger sandwich will undoubtedly plump you up more than the smaller one. If you think otherwise you have no idea what you're talking about.