They have different taste.
Usually a regular cup is 6 oz ( 177ml ) have-here, 8 oz ( 237ml ) takeway, and a large cup is 12 oz ( 355ml ) for BOTH. Most Cafes have 1 oz ( 30ml ) of espresso in a regular cup, and the large one will have 2 oz ( 60ml ) of espresso.
See the difference? There was more ( 2 oz=60ml ) milk in REGULAR TAKEWAY cups, meaning the regular takeway drinks taste a little bit weaker and milky.
There are also other sizes such as 16 oz ( 473ml ), 20 oz ( 591ml ) and 25 oz ( 739ml ), mainly for elderly customers who are after a hot 'coffee flavoured milk'. we recommend cup sizes of 6-12 oz, that will be healthier for customers.
A latte or cappuccino should taste like a good balance between milk and espresso. The problem can be resolved to downsize the regular takeway cups, that would be the same taste between regular and large.
It's not for no reason that we use 6.4 oz ( 190ml ) cups for Cappuccino's in the Barista Competitions.
Regular or Large? 6 oz or 8 oz ? How would you like your coffee? ☕️