What is happening underground first
Start with the water already in the soil, not the concrete. Water expands when it turns to ice, and ground holding more moisture in one area than another expands unevenly as the cold works its way down. A spot that stays wet, low ground where water collects, or shaded soil that stays colder longer all freeze harder and lift more than the dry ground a few feet away. That difference in how much water is sitting where is really what decides whether you get frost heave at all.
None of that has anything to do with the concrete mix itself. It is entirely a question of how much water is sitting in the subgrade, the native ground a slab, a walk, or a footing actually sits on, and how cold that ground gets before spring.
What that does above ground, depending on what is sitting on it
A footing is set deep enough that the ground under it stays below where winter freezing reaches, which is the whole reason frost heave is not supposed to be a foundation problem on a properly built footer. Flatwork lives in a different world. A driveway, a walkway, a patio, a garage floor without a foundation under it, all sit at or near grade, right inside the ground that freezes every winter. Some seasonal movement on a slab like that is normal and expected. What you are watching for is not zero movement, it is movement that is even across the slab rather than concentrated in one corner or one panel.
That difference is also why a garage floor poured on a slab foundation gets treated more like flatwork than like the footing under a stick built house. If there is no deep footing under it, it is living in the same frost zone a driveway does, and it is worth asking about at the estimate if you are planning one.
Telling heave apart from something else
The direction is the first clue. Frost heave lifts. A slab that has dropped, or a settlement crack running through a section sitting lower than the rest, points the other way, usually ground underneath that compressed or was never packed well to begin with. The pattern is the second clue. Heave tends to follow moisture in the soil, so it shows up worse near a downspout, a low corner of the yard, or shaded ground that holds water longer than the rest of the site.
Timing is the third clue. Settlement tends to show up gradually over months or years as ground compresses under a load. Frost heave tracks the season directly, worse in the coldest, wettest stretch of winter and easing back as the ground thaws, which is itself a useful way to tell the two apart if you are watching a spot over time.
When it is worth a call
A little seasonal lift that settles back down each spring on an older slab is usually nothing to act on. What is worth a phone call is heave that gets worse every winter instead of settling back, a joint or a panel edge that lifts enough to catch a shovel or a plow blade, or lift concentrated at one corner while the rest of the slab stays flat. That pattern almost always points at water getting into the base under that one section and having nowhere to go before it freezes, which is a drainage question we can look at, not something you have to guess at from the driveway.