Big difference, great tube amp just makes your guitar sing and it's totally different feel from the solid state amp.I thought I could, and spent years in a "tube only" phase. But this past week or so, I've come to the realization that it was all in my mind. Now, I can tell the difference between a good and a bad amplifier, regardless of technology. And I have owned bad tube amps and bad solid state amps; however, as far as tube "warmth", "dynamics", etc., I simply don't hear it. The seeds of doubt began a few years ago when I had a Fender Frontman with a built-in LED distortion circuit. I also had an ADA MP-1 which was the rackmount tube preamp of the late-80's into the early 90's. Anyone who was anyone had one of those. I plugged that MP-1 into the Fender Frontman clean channel, A/B'd back and forth between that and the Fender's distortion channel (with the MP-1 bypassed), and with a little gain and EQ tweaking, both sounded identical. The LED distortion of the amp sounded exactly the same as the MP-1.
"Dynamics" is one element that tube amplifiers supposedly excel in (responsiveness to picking), but every single amp I've played through, tube or solid state, would respond dynamically if the gain knob was set right. "Warmth"? I've been fooled plenty of times by what I thought was a tube amp that turned out to be solid state. I thought I got a fantastic deal on a Hughes & Kettner tube rack preamp when I was stationed in Germany. The price was great for what (I though) I was getting based on the tone I heard in the store. I opened it up to see how many 12AX7's were in there and all I saw was a circuit board...
Of course, there are things like tube rectifier "sag" that is exclusive to tube amps, and that is something I've never really had a thing for, though I understand some people love it. But as far as tone itself and dynamics, no - I can't hear the difference. Odd and even-order harmonics? Can't hear the difference.
I'm open to the possibility that if I sat down with one good example of each, and spent some time going back and forth, there might be something I'd notice, but that "something" just might be the difference between two different amplifiers anyway.