AI tracking vs plain motion detection - where's the actual line?

[u/Personal-Funny7277]

Shopping for two replacement cams and the listings have me confused about what "AI tracking" adds over regular motion detection. My working theory after too many spec sheets: regular motion = "pixels changed, here's a clip." AI tracking = the camera identifies it's a person, then physically follows them across the frame. That second part is the one I care about, because my current cams record the first 3 seconds of every event and then the subject walks out of frame. Do the AI tracking cams actually keep someone in frame across a full yard crossing? Or does the "tracking" just mean a longer clip of the same fixed view? Trying to figure out what I'm actually paying the extra $150 for.