All-In-Ones, or AIOs, are pretty simple to understand and use. A post on these would be pretty short (except for the pics!). Some of the disadvantages of AIO's lead mamas to try pockets, so I thought I would treat them in the same discussion.
All In One's:
These diapers are just as their name implies - the diaper is all in one piece. These diapers are most similar to disposable diapers, and therefore are sometimes the choice of mamas wanting a simple cloth diapering option for daddies, grandmas, babysitters, daycare, or going out and about.
Thirsties AIOs front and inside
Nana's Bottoms newborn size AIOs front and back (top) and inside
Nana's Bottoms Action Shots: periwinkle is preemie size, the mauve is one of the newborn sized ones:
There are downsides to AIO's. Some take a long time to dry. (Others take very long!) I was always concerned about them getting really clean since there isn't a good way for the sudsy water to circulate well into the absorbent part of the diaper.
All In Two's:
Related to AIO's are AI2's, diapers that are still a single-use diaper, but the absorbent material can be removed for washing and drying. I have much less experience with these, since the ones I tried I didn't like much.
Bottombumpers AI2 - the long insert piece snaps out for laundering
I hate putting pockets this far down the post, because THESE ARE THE DIAPER I WOULD RECOMMEND to mamas starting with cloth diapering. If the idea of getting prefolds on your babe is what keeps you from trying cloth diapering, this is the system for you. I've always had a few pockets in our stash from the beginning, but now that I have more for daycare, I find myself using them even at night and on weekends. They are just so simple.
The pocket diaper is literally a pocket. The outer portion of the pocket is the waterproof material, usually PUL (polyurethane laminated polyester, mentioned previously). The inner layer that forms the pocket is usually fleece. Most fleece is "wicking", meaning it can transfer wetness and has a "stay-dry" feeling because the moisture is transferred to the absorbent material underneath. This makes pockets an especially good option for nighttime.
There are LOTS of options for the absorbent material inside the pocket - enough for a separate post!
The advantage to pockets over AIOs is that the absorbent material can be removed from the diaper to be washed, so you know that it is getting clean. Since it is a separate piece in the dryer, it usually takes less time to dry. A disadvantage is that the insert has to be "stuffed" back into the pocket after the laundry in order to have your diaper ready to use again.
Another advantage to the pocket - and again, this will be treated in the post on pocket inserts - is that you can customize the amount of absorbency you use to stuff the pocket. Have a heavy wetter? Add more absorbancy. Taking photos in a special outfit and need a trimmer diaper? Use a thinner insert - if the diaper is only on for a short time, absorbancy might not be an issue. Nighttime? Stuff away.
I have tons of photos of Wee One in pockets, since she's in them the majority of the time now. Of course the cow print diaper was a pocket, as are the Thirsties Duo Diapers that I rave about, and the Knickernappies OS that I won.
Thirsties Duo Size 2 in Meadow
Raspberry Knickernappies size Medium
Swaddlebees Size Small - when she was still less than 6 pounds. This is the first pocket I tried on her. Below are the photos I took when I sold these on Diaperswappers FSOT.
I started out buying sized pockets (size small, size medium) since I think they fit smaller babies better. Now that she is bigger, we can take advantage of the one-size (OS) diapers. The idea is that one-size-fits-all, which is why they are referred to as OS diapers. There are usually snaps that adjust the rise, and allow you to fold and snap down the front for smaller babies, then adjust as your baby grows. There are usually more snaps around the waist or longer aplix across the front to accomodate babies as their waist grows larger. The advantage is that a single diaper can fit babies of different sizes if you have two in diapers, or can fit your baby as (s)he grows. The disadvanges are that I don't think you get as good a fit on small babies like newborns, and the folding down and adjusting can create some bulk. I've also heard some OS get too small for big toddlers.
Thirsties has tried to address this issue with their line of Duo Diapers. The Duo Diapers have snaps in the front to adjust the rise so the diaper accomodates different sized babies. However, they come in two sizes, Size 1 for newborns and smaller babies, and Size 2 for bigger babies to toddlers. Wee One is in Size 2. I have to say I think these diapers will last her until she's out of diapers, because on the largest settings, the diaper is huge. However, it adjusts down to fit her now at 18.5 pounds and is still trim and not bulky.
Some popular OS diapers, in addition to the Knickernappies and Thirsties Duo, are the BumGenius brand.
BGOS blossom compared to Thirsties Duo Size 2 Storm Cloud, and both on her.