I had a chance to compare the systems, too but my conclusions are completely different. Teachers at the physics/math lyceum I studied at were emotionally unstable psychopaths with mood swings. They could switch from calm "kids, if you don't understand something, please, don't hesitate to ask" to the screaming at the top of their lungs of "are you a stupid imbecile? what a moron you're to ask that" just a minute later.
It was all about rote memorization. Rules, theorems, axioms. Not just the way to prove or principle behind, but the textual representation (to the teacher's liking) word-to-word. Of course, there was a division of students into multiple groups, and those with important parents had an easier time. Any of their bullshit was always graded as "A". But those actively disliked could get "F" for a perfect work. A dot at the end of the sentence is missing? "Go back to the kindergarten where you belong". Something is crossed? "What is it, a toilet paper? Go use it for wiping your ass" (they could tear it apart in front of you). So, the representation/look of the work always came first. A teacher was a lawyer, prosecutor, and a judge at the same time (just what some Americans wish to have as a state): you don't like something, go f___ yourself.
The textbooks. If you compare the best Soviet ones with some average American, you can come to the conclusion that Soviet are so good ("exercises are something to behold", "high quality in their expression", etc). But the best American books wouldn't give a single chance to the Soviet ones. In fact, even some Russian Empire textbooks so much better than Soviet (not to mention Russian), they are getting popular among parents for homeschooling (schools can't use books unauthorized by the ministry of education). The best American and pre-Soviet textbooks are born out of lectures, author's personal experience with students. Soviet authors are disinterested observers who don't care. Textbooks, apparently, were the product of central planning like process (so they were getting worse and worse, the further they went from Russian Empire epoch).
And finally, a thing that really deeply touched me at a western University. A teacher when asked a question once said "I don't know, I have to check it". Holly f... Someone who openly admitted they don't know something, no freaking way! Back at the lyceum it would be "Shut your mouth with your stupid question, we don't have time for that". Then she would find the answer and during the next class say something like "now when we have a few minutes, I'll do you a favor, here is the answer... What a moron you're not to be able to conceive this yourself".