Suitcases are the same as luggage, but you cannot say two luggages as luggage is a mass noun. When you travel you have luggage, or two pieces of luggage. Mass nouns use measure words like pieces of to make plurals.
People Also Ask
This type of noun is called a noncount noun. Things like milk, air, homework, and luggage are noncount nouns and do not have plural forms. (Click here for a list of more noncount nouns.) Below are some examples of much used with noncount nouns.
Common nouns are everywhere. Look around you now and you will see many common nouns: door, window, tree, sky, cat, truck, road, computer, phone, bottle, ball, luggage, people, hair.
Technically, any piece of luggage that you “carry on” to an airplane is a carry-on bag. Most airlines allow one piece of carry-on luggage or “hand baggage” that can fit in the overhead bin, plus a “personal item” (a smaller purse, computer bag, diaper bag, small backpack, etc.