Bags : Luggage
Bag
A bag is used for packaging and/or carrying items. For the latter a bag may have one or two handles; a shoulder bag has a strap to carry it on the shoulder (the bag is either carried on the side of the shoulder carrying it, or the other side). A rucksack has straps to carry it on the back. A bag may be closable by a zipper, snap fastener, etc., or simply by folding (e.g. in the case of a paper bag). Sometimes a money bag or travel bag has a lock. Sachets may be fabric bags that are filled with pot pourri and tied off with ribbons. A bag may or may not be disposable; however, even a disposable bag can often be used many times, not only for economic but also for environmental reasons. On the other hand there may be logistic or hygienic reasons to use a bag only once. For example, a garbage bag is often disposed of with its content. A bag for packaging a disposable product is often disposed of when it is empty.

Luggage
Luggage is any number of bags, cases and containers which hold a traveller's articles during transit. The modern traveller can be expected to have packages containing clothing, toiletries, small possessions, trip necessities, and on the return-trip, souvenirs. For some, luggage and the style thereof is representative of the owner's wealth.Luggage has changed over time. Historically the most common types of luggage were chests or trunks made of wood or other heavy materials. These would be shipped by professional movers. Since the Second World War smaller and more lightweight suitcases and bags that can be carried by an individual have become the main form of luggage.

source : wikipedia