I want so much to say that there is a difference, but I would also have to admit, that the Placebo effect comes into play.
It also depends on your setup too, both the audio device and the speakers.
For low bit rate MP3's the difference is obviously going to be more obvious than high rate ones, and then it can also come down to what style of music you listen to too!
Rock music for example wont ( in many cases ) show any differences, while a classical / smoother sounding track, might show it.
I have a mate, who swears by FLAC and he says that MP3 are awful, but I taught him about bitrates, and that he was judging MP3 by lower rates, and so I converted one of his albums to 320 and 192 and to 96 to show him that not all MP3 files are encoded the same way. I was also showing him that the smaller the file, the better the compression and space saving, but at the cost of quality. The FLACs were 480Mpbs.
For a giggle, I also converted to a samplerate of 11K and a BitRate of 32 just for a giggle... Interesting! - Reminds me of my SoundTracker days on the Atari ST LOL
He did conceed, that the 320 were very high quality, and I will also conceed that the encoding might have done something because the original FLAC definitely did feel to be better quality? - Whether this was both of us feeling it, or if it truly was better, I guess you can ague that, but the fact is, that the FLAC did indeed seem to be better than the MP3 no matter how high quality we did it, but, the size of the files in FLAC are much larger and even at very high quality, the MP3 are half the size, and not really distinguishable from FLAC... Not really!
Anyway, we had fun and now he had gone to MP3, even though for years, he has sworn by FLAC, and now he has the huge benefit of saving at least 50% of his Storage space.