There is a fair difference
Although the X1 is being built by HTC, it was designed and specified from the ground up by SE. It therefore uses SE cameras and screens etc ... this should provide still and video along the lines of an N95 - much better than the toy town stuff on other HTC devices ... which is a huge difference - I currently have a TyTNII and N95-2 ... it will be nice to lose the latter.
Also .. whilst I agree about the pitch, VGA often provides little real extra screen estate than qvga - it just looks prettier. WVGA provides utilised extra estate for apps - I noticed this on the G900 ... so it is far far more practical the VGA.
I too have BT Stereo ... but having a real headphone socket is great.
The manual for the X1 also said it had proper hardware GFX acceleration that was exploited. It may well be that it isn't optimised at the moment but at least we shouldn't have the nightmare we had with the TyTN II where HTC refused to develop the drivers for the embedded hardware.
My hope if that the display is decent in outside light. The TyTN and TyTN II weren't great and the G900 was a disaster in this area.
Other things ... I suspect the radio will be at least of the spec in other SE devices like the T650i my wife has. The N95 one is unusable ... I suspect this will be much better than HTC designed gear.
I'm sure there is more ... but ... I think it more than differentiates itself from the pro ...