Look closely at the definition of what the "real time" numbers are telling you.
Real time 1 day: look at the documentation. It doesnt state you have to qualify that particular day. What it really says is that a device that was qualified was seen that day. Meaning; you have qualified for the segment at some point in time (whitin the traits TTL and the segments recency) - regardless of if you qualified for the segment yesterday OR at a previous visit. So if you qualified for the segment 10 days ago, and you visted the premises again yesterday (any random page sending data to AAM) with the same device, you will surface in the 1 day count number for the segment. - a qualified device was seen by adobe.
If you use a device graph (device stiching) the pieces will fall into place since the numbers then will be inflated by also adding all cross-device units associated with the profile (its then the profile that has been qualified) that visited your premises yesterday.
To replicate numbers seen in AA you have to look at this on a Trait level. But; segments made out of several traits could then be subject to "correction for double counting" e.g. you could count as one in each trait since you have exhibited all traits, but only show as one on a segment level. Its complex.
You will find a perfect match between an individual trait real time numbers and numbers in analytics with a 24 hr delay (so not so real time after all).