Here is a general overview of the different types of cloth diapers and inserts available today.
Flats – the classic cotton single-ply material which is folded to fit baby and secured with diaper pins or a snappi – often thought of as how mom used to cloth diaper. These require a cover to keep them waterproof.
Prefolds – these are rectangular pieces of fabric 'pre-folded' and sewn into 3 panels of differing thicknesses. The number of layers in each panel is referred to as the ‘ply’. The outer two panels usually have anywhere from 2 to 4 layers (ply) of thickness. The maximum absorbency is found in the center panel – anywhere from 6 to 8 layers. So if there are 4 layers on the two outer panels and 6 layers down the center, the ply would be 4x6x4. These are generally pinned or snappi’ed to the baby and then a cover is required.
** Flats and Prefolds are generally your least expensive choice when it comes to cloth diapering your baby.
Fitteds – Most resemble a disposable diaper. They are contoured to have an hour glass shape and have gathered edges around the legs. They require no folding and are made of soft cotton like a prefold. They are fastened with either snaps or velcro tabs (aplix) and require a cover to keep them “waterproof”.
Covers - Lots of different types of covers are available such as plastic, nylon, fleece and wool. These are available in snaps, velcro and even pull-on. Thinner materials are generally used during the day whereas fleece and wool are more commonly used at bedtime since they help contain leaks better.
Pockets – The newest types of modern diaper on the market today. Pocket diapers are two piece diapering system made typically with a piece of fleece that makes up the inner portion of fabric and a waterproof layer that makes up the outermost portion. Then an absorbent material is placed inside of the two pieces making the whole system act as an all in one system that keeps babies dry. The inner piece is generally microfiber, hemp or a combination of the two. Prefolds can also be used as an insert. Pocket diapers are available in both aplix and snaps.
All in Ones (AIOs) – These are fitted diapers that have an outer waterproof layer and have absorbent layers sew in to them. They are similar to a pocket diaper, however the insert can not be removed. They are not practical for daily use since frequent washing and drying reduces the effectiveness of the waterproof outer layer, however these diapers are ideal for out of home use.
One Size Diapers - these are similar to pockets (and all in ones), since they are one piece, and have an insert that needs to be stuffed into a pocket. However, these diapers are adjustable (either via snaps on the front, or by hidden elastics), to grow with your baby. They generally fit best starting at 9lbs and on their biggest setting would fit about 35lbs. While these are definitely a money saver, they are usually best suited if you are on your last child, or are only have one child since they don't have as long of a shelf life. Also consider that most people find on the smallest setting they are bulky on babies.
Inserts - Inserts come in a variety of material from microfiber, hemp, fleece, cotton or a combination of those listed. Prefolds can even be used as inserts. Generally inserts are used to "stuff" pocket diapers to absorb urine. The inserts quickly wicks away the moisture to keep your babies skin soft and dry.
Doublers - Doublers can also be made out of the same materials as inserts. They are basically used to add extra-absorbency at bed time, nap time or long car rides.
Liners - Liners are generally used to protect the inside of the diaper from diaper rash cream, but they are also used to make it easier to remove poop from the inside of the diaper. Liners usually come in fleece (and can be washed and reused) or as biodegradable flushable "papers".