The auto finishing product business is unregulated in terms of product descriptions so they can make and call stuff whatever they want to as long as the promises on the labels are suitably vague enough to keep them out of court. I think sealants and glazes are just more stuff that has been created to sell to you. The only observation I can make is that I think sealants seem to be classified as a more durable form of of synthetic based final protection than wax. My take is that the glazes that are in liquid form seem to be a final polish with very fine abrasives.
In the products for managing paint finishes, there are two rather broad product descriptions, polishes and surface protection. In general, polishes remove surface defects (fine scratches / scuff and swirl marks) and waxes or sealants try and protect the surface.
All polishes contain micro abrasives. They remove scratches and marks by leveling (removing) finished paint around the scratch so that it is no longer visible. If the paint is in good condition (no scratches or oxidation) I would not use anything that contains a polish because you are removing a bit of the clear coat each time. Polishes run a fairly large gamut rangeing from paint correction compounds to polishes intended for more frequent use. When I got my NSX I did a paint correction using a dual action buffer with an initial treatment using Meguiars M105 (moderately aggressive abrasive) correction compound followed by Meguiars M205 which is closer to a final polish compound. Mequiars calls M105 an ultra cut compound and M205 a finishing compound. Just to screw with your head they refer to both products as ultra glaze; but, they are not the same as the glazes that are sold in a bottle as 'glaze'. I went over the car once with the M105 and have not made a general application of the M105 since. If I get a scuff mark on the clearcoat I will remove the scuff by spot polishing with M205 and probably every 3-4 years do a light treatment of the complete car with M205 to remove the marks that inevitably seem to show up from washing and drying. I have used the M105 as a spot treatment once or twice if I get a very aggressive water spot that will not come out with the M205.
When I did the initial M105 - M205 paint correction treatment on the NSX, after finishing the paint correction, as an experiment I did apply a 'glaze' product to 1/2 of the trunk lid using the DA buffer. On a surface that had just gone through the paint correction process there was no discernable difference between the glazed and unglazed side of the panel. As a result the remains of that bottle of glaze has been sitting unused on a shelf in my garage for 7+ years. Perhaps on a slightly deteriorated paint surface a glaze might provide some level of polishing.
On the NSX I use a carnauba paste wax which does not contain any polishes or cleaners. It is not a liquid, more like a lump of soft candle wax. It looks like and probably is the same as the wax that people used to apply to their wood floors and furniture 60 - 70 years ago. It goes on easy and removes easy. I can apply it to the whole car, go have a beer and then come back and it removes easily. Do not try that with the waxes that come packaged with cleaners / polishes. If the carnauba wax is in a pourable form it is not 100% carnauba wax. The carnauba paste wax is probably not that long term durable; but, for me that is less of an issue because it is easy to re apply and clean off after a couple of car washes.
I do have a 2021 Audi allroad which gets bumped to living outside when the NSX comes home from winter storage. I have experimented with paint sealant on the Audi instead of wax because of their claims to longer durability. For me, the jury is still out as to whether the sealant is a better product. If I use the measure of how well water beads after the car has been washed the sealant is not hands down superior to the NSX with wax. But, the NSX gets stored in the garage versus being out in the sun so its not an exact comparison. If I wanted a better comparison I would seal 1/2 the Audi and wax the other 1/2 and then wait and see how they looked after 3 months; but, I am too lazy for that. I will note that the paint sealant is a lot more hassle to apply and remove. The Audi has rubberized black trim around the wheel arches and if you get sealant on that trim and it dries you will be going f***. When my bottle of paint sealant runs out I don't know whether I will continue with the sealant or just switch to using paste wax on the Audi. The Mequiars M21 Mirror Glaze sealant (there is that glaze word again) was not inexpensive. 2023 Apr 5 update. I just washed my Audi. Based upon how the water didn't bead I conclude that the M21 will not make it through 5 months of winter in Saskatchewan.
If the paint looks 'new' then use a wax or a sealant for protection. You get to choose which. I prefer old school paste wax. You can try an application of glaze before the wax / sealant; but, I am not sold on the benefit of glazes. If the paint no longer looks new then you need to go through a paint correction process to restore the finish (this would include the clay bar treatment as part of the pre cleaning). How much correction and the types of pads and compounds will depend on the condition of the paint. I have a Porter Cable 7424 DA buffer and it comes with a nice DVD on the whole correcting, polishing, waxing process.
As bullithollywood notes, polishes remove the final finish. Don't polish if you don't need to.