There are some minor differences, hopefully these links will help. I have no relation to this company just the one that I always buy these binders from and have actually bought these already. I'd be willing to bet all the sellers are selling the same thing since they all have the same watermark over the pictures. All of them do a good job at getting me flat, the ones with elastic on the sides are easier to get on but do stretch where as the one without the elastic takes more work and hasn't stretched at all since I bought it 5 months ago.
Not sewn into a tank top, no elastic on side opposite the closure. Thicker panel almost like thin padding and gets me extremely flat:
http://www.ebay.com/itm/251245214720Sewn into tank top, elastic on the side opposite than closure. Firm panel but not as heavy as the first one listed.
Very slender fit and has a feminine look to it if you're seen without a shirt over the top. I don't wear this one often as my preference is either the first one listed if not seen or the other looser fit tank top binders that can be worn with or without a shirt over the top.
http://www.ebay.com/itm/251245214731Sewn into tank top, elastic on the side opposite than closure. Firm panel but not as heavy as the first one listed. Looser fit and looks like a normal tank top without the need to wear a shirt over the top. These are both the same, just different colors.
http://www.ebay.com/itm/251245214705http://www.ebay.com/itm/251245214760This one used to be like the two tank top above (251245214705 and 251245214760) but the sizing chart changed and now is the same chart used for Item #251245214720, so there is a chance the style of binder inside has changed as well. I'll be ordering another of these as soon as they have my size available in white.
http://www.ebay.com/itm/251245214744Strapless, looks otherwise like the first one listed but I can't comment personally on this as I don't own one (just not my style):
http://www.ebay.com/itm/251201605606*IMPORTANT SIZING*
As far as sizing goes, just follow the chart on each page and you'll be good. Notice the charts on the two links below. If you were 88 cm for example, you would be large for the first link but medium for the second one. I don't know why they don't keep sizes vs measurements consistent across all the binders but I've found that the chart on each individual listing has been accurate for me anyways.
http://www.ebay.com/itm/251245214720 (88 cm = Large)
http://www.ebay.com/itm/251245214705 (88 cm = Medium)
Hope this helps. If you have any more questions, just let me know.