Still trying to understand.. what are dog ears vs fat pads

Dog ears do usually contain fatty tissue, but they also tend to have a distinct 'pointed' or 'winged' look to them and also tend be puckered looking around the incision area, and/or have obvious excess skin, where excess fat tissue would likely just lay a bit like a relatively normal looking fat roll.

Both can usually be revised; depending on how the chubby parts of my chest settle down in the next few months, I may ask to have the fattier areas under my arms (that are not dog-eared) to be lipoed a little to flatten them out and take the roll away.
Or, since they're just fat pads, if I were to exercise and watch my diet a bit they'd probably go down on their own, but if lipoing them out is covered as a 'revision', I'm fine with taking that way out as well.

The dog ear, however, is caused both by fatty tissue, some extra skin, and by how the area was stitched up, so losing weight likely won't affect it much and it'll have to be cut back open, lipoed out, and the stitch redone a bit tighter to prevent it from happening again.
My PS told me they do that in the office with local anesthetic and she uses dissolvable sutures so I won't have to come back in to have stitches taken out; 'downtime' is about 2 weeks of just making sure you don't pop the incision open by doing too much upper body exercise, but it's otherwise like just kind of a "bad cut" in terms of healing and how much the revision hurts.
I only have a dog ear on one side, where the incision went further under my arm, and with the amount of swelling that happens it's easy to see how there might be extra skin or tissue left as they don't want to take too much then make it difficult to close or heal properly.

Mine is super small (you can see it here if you want to look), but some people get dog ears that are rather large and get in the way or get pinched with normal arm movement; it's more common in overweight patients, but can happen to anyone.

Dog ears are usually pretty obvious too, like, even early on. I noticed mine the second week. It has gone down a little as swelling has gone down, but it's still obviously got a 'point' on it and is still obviously a dog ear that's going to need a revision. The other side, to me, looks and feels like I'm just...kinda chubby and would likely resolve if I got around to taking off those 20lb I need to lose anyway.

My PS did tell me that she didn't want to do anything with it for at least 6-8 months (6 months being the minimum, she did tell me she preferred to wait at least 8) if it's not causing issues or pain, because swelling can make it difficult to get the revision right on the first try and she'd prefer I wait until all swelling has completely resolved before we go ahead with any dog ear revision or lipo.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC36658... explains dog ears pretty well in a medical context.

After DIEP, I had points at the ends of my incisions, both under the arm and at the hip. I also had excess rolls of fat which looked bad. My first PS would only remove the points. My second PS lipoed the fat. Much better appearence.

Dog ears can be pretty big; mine is super small and doesn't cause any problems beyond me not liking how it looks, but others can be large and easily pinched or constantly sore and in the way.

One of the photos at this link shows a fairly large one before and after revision: http://breastfree.org/photos.php?ref=120

They can also be un-pointy, but still like a 'bunched up' bit of fat, as seen in this pic, and this pic is a decent look at abdominal dog ears (after a tummy tuck or sometimes the types of surgery that take tissue from the abdomen to reconstruct the breast).

Some plastic surgeons, like debiann mentioned, will only treat the 'pointy' obvious ones, while others are willing to lipo the whole area to make it lay more flat.

Edit to add: While I am a little bit overweight (maybe 20lb), mine was more than likely caused by the fact that my breasts were large (34DD, and a bit saggy).
The larger your breasts were the more likely it is to happen, and if you happened to have large breasts AND be overweight, there's even more of a chance that you'll end up with some level of dog earing; it's annoying, but I'd rather have that + a revision than have them accidentally remove too much skin or stitch it up too tight and have initial healing difficulties.