Do you think Buran had the same design problems, or shared majority of them, with the Space Shuttle? Or from technological point of view, it could be more successful?
With the benefit of hindsight, what would you do with these two projects if you were in charge of them in 80-s - close them, may be try to fix or redesign some parts?
It shared most of the big design problems, fixed a few of them, and likely had a bunch of problems unique to it, as all complex space vehicles do.
What Buran got wrong: It shared the layout of being a side-slung spaceplane that hangs off the booster rather than being stacked on top which makes it nearly impossible to abort during a launch. It also had the Shuttle's insanely large wings which were another liability. These two issues alone were probably the biggest flaws of the Shuttle design and Buran shared them.
What Buran got right: It did not use foam on its central rocket engine core and it allegedly had a more durable thermal protection system. The lack of foam meant there was no foam to shed and impact the orbiter. The more robust thermal protection system is also an obvious advantage, but we'll explore this point later. The fact that it did not reuse its main engines or boosters was actually probably a cost-saving feature as refurbishing these on the Space Shuttle proved to cost far more than manufacturing more for each launch due to their complexity and the lack of economies of scale in repair work versus fabrication.
Things that didn't matter between the Shuttle and Buran: Much has been made of the inherent danger of solid rocket motors because they can't be shut off in flight. There has never been to my knowledge an instance where the ability to shut down a solid rocket motor would have made any difference to the outcome of the flight. In other words, when a solid rocket motor fails, the mission fails and shutting it down would have not have fixed it.
"But liquid engines can be shut down!", yes, but usually no. For most vehicles, the loss of a liquid engine would still be the loss of the vehicle even if you could shut it down before it exploded. There are rare examples of rockets with some engine-out capabilities but even then, the loss of an engine in certain parts of the flight will still mean the loss of payload. The Falcon 9 is notable for having twice lost an engine and then clawed to orbit, but on one of those missions it still had to ditch a secondary payload into an unusable orbit.
Solid rocket boosters are also used early in flight to help a fuel-laden rocket get off the ground and gain altitude. This is the single most critical period of flight for a rocket and even for those liquid rockets with proven engine-out capability, a loss of engine within the first 30 seconds of flight is almost a guaranteed failure. So yeah, a loss of a solid rocket is an automatic failure whereas the loss of a liquid engine is "only"
usually an automatic failure rather than always a failure. It's close to a distinction without a difference and for sure the explosion or even shutdown of a liquid rocket booster on Buran would have been just as deadly as it was for the Shuttle.
What we don't know: A lot.
While NASA certainly pushed out a lot of what we may consider to be propaganda about the virtues of the Shuttle, it was still developed in an open environment with a free press investigating all aspects of it. And they did! The press was at times super critical of the Shuttle, especially in the lead-up to Challenger when the Shuttle was failing to meet launch and cost targets. There were also open Congressional investigations and hearings which went over the flaws in detail.
The Buran was instead developed in secrecy and mostly kept that way. So while we can point to NASA's mischaracterizations of the risks of the Shuttle, we can also point to the blueprints that tell the truth, along with Congressional testimony and press investigations that differed with NASA's conclusions. Compare this to when retired Russian engineers boast in interviews that the Buran had a far superior thermal protection system, for example - we are less able to determine the truth behind that statement because of the closed environment in which it was developed. We do not have detailed schematics to go over, or press investigations, or anything like that. And the Buran only flew once, with many systems not installed, so we don't even have a track record to compare them with.
So with regards to the tiles, we could ask, What parameters are better? What parameters are worse? If the thermal tiles were different, then the parts which interfaced with them were also different. Did the changes required to these interfacing parts make them better or worse than the Shuttle's equivalent system? If the tiles worked in a different manner, did this require Buran to use a different flight profile - and if so, was this flight profile more or less safe than the Shuttle's? Etc, etc.
I actually believe that Buran's thermal system was better, but it's hard to tell with certainty and it also does not preclude the Buran from having its own unique and serious safety flaws which we do not and will not ever know about. I also personally think the Buran is cooler if only because it didn't kill 14 people and set an entire nation's space program back
twice.