Similar, but not the "same". Conversion varnish= large manufacturing facility that can deal with all of the environmental regs needed to be able to use the tougher wearing stuff. Can be water based or oil based. The toughest hardest wearing finish available. Catalyzed lacquer=shop built, but with decent technology enough to be able to spray a decent, but not the best, finish. Can chip easier if you have rollerskating kids or drop a soup can on it. Stands up to everyday wear OK if the maker has purchased one of the better quality systems. There are all manner of quality coating available though, and some makers cheap out badly here just to have the "name". Any of these is better than site sprayed or brushed. That's the low end bugs and dirt in your finish that fails before the year's out but only came with a "tail light warranty".

I agree that a high quality exterior oil based primer would be best and the best topcoat would be 100 percent acrylic. Sprayers are actually more designed for oil based coatings than latex coatings. The best thing to run through a sprayer is actually lacquer. Ever since latex/acrylic coatings became the main coating we run through our sprayers, our maintenance on our sprayers have been more costly. Also, for exterior wood priming, spraying may not be the best thing. The best protection you can give to wood comes from penetration of the coating, which can really only be achieved by pushing the product into the wood pores with a brush or roller. You can actually use the sprayer if you wish to get the material on faster and then backbrush it. I would opt to backbrush or backroll the topcoats as well. The absolute best thing you can do is backprime the wood as well, prior to installation (prime all sides). Cut your boards, and prime the end grains too...the part of the wood that gets buried in the ground. That is usually where moisture enters and the wood will start degrading there and move upwards...anything you can do to slow that process will help the life of your paintjob. As a rule of thumb, I always tell people that wood sitting on grass, in the dirt, etc. is really void of any warranty that I could offer or the manufacturer of the paint could reasonably stand behind. Wood sitting in rain, snow or mud just isn't going to hold up long term.

Did you stir the can before using? There is an additive in the otherwise gloss poly to make it satin that settles out when the can sits on the shelf. Do not shake the can like paint as that creates air bubbles which are a nono with poly. If you did not stir, go ahead and stir before the third caot---that will make the coat satin and less shiny.

Sherwin Willams Pro- Classic does get good reviews, and I have read of many that do use it for cabinets. I think it would be a fine choice. Read through the links articles below to get more information. https://dengarden.com/home-improvement/Sherwin-Williams-Pro-Classic-Paint-Review https://www.hometalk.com/3173018/q-sw-s-proclassic-vs-bm-s-advance I would not go with anyone that insists on using a "proprietary" paint.