Grands and pianos are classified depending on their sizes:
Baby grands – less than 5`8“ (173cm)
Grands – 5`8“ – 8`10“ (173-269cm)
Concert grands – over 8`10“ (269cm)
Uprights:
Spinets – less than 38“ (97cm)
Consoles – 38“- 44“ (97-112cm)
Studios – 44“- 51“ (112-130cm)
Full size or professional – taller than 51“ (130cm)
For more accuracy each brand name piano has own model designation. It could be only a letter or letters, a number or combination of letter and number.
Note: Spinets and consoles were introduced in 1930