Tube Watts vs. Solid State Watts - Any credence?


I've heard numerous times that Tube watts are not the same as Solid State watts when it comes to amps running speakers. For example, a 70 watt tube amp provides more power than a 140 watt solid state amp. Is there any credence to this or just sales talk and misguided listeners? If so, how could this be? One reason I ask is a lot of speakers recommend 50 - 300 watts of amplification but many stores have 35 watt tube amps or 50 watts tube amps running them. More power is usually better to run speakers, so why am I always hearing this stuff about a tube watt is greater than a solid state watt?
djfst
I was just about to ask the same question.

I moved from Dynaudio's at 86 dB to Vienna Acoustics Kiss at 89 dB, both into 4 ohms and am looking to change my amp from a Krell FPB 200c to a tube amp - either a Conrad Johnson LP 125 sa or a Cary CAD 120 S Mk 2 both at 120 plus watts vs the high current Krell which doubles down into 400 watts.

Will I get sufficient watts from either of the tube designs? The manufacturer recommends 50-180 watts and received wisdom seems to be that the speakers respond better to solid state watts (what does that mean)?
It might actually be true that: "...a 70 Watt tube amp provides more power than a 140 Watt solid stat amp." if used on speakers with an impedance of over 16 Ohms.
But, selecting an amp involves more than just this issue, there are other variables to consider.
High end audio is definitely tricky. For example, I'm running a Primaluna Dialogue HP Integrated Amp with EL34 tubes to Sonus Faber Olympica III Speakers which are 91db efficient and are 4ohms rated according to specs. The Primaluna has 4ohm taps and 8ohm taps, and the 4ohm speakers sound far better on the 8ohm taps.
I don't remember where but once I read that someone was comparing the sound of 100 wt Gryphon with 600 wt Krell, both transistor amps. Same speakers,forgot what that was. Besides sounding a lot better in every respect, Gryphon also sounded more powerful. Dynamic speakers, this I remember.
What are the possible explanations?
Uh - a watt is a watt ...it is a unit of measure there is no difference by virtue of the device that produces it.

Now frequency characteristics, load interactions and clipping or distortion characteristics- that is different.