HKLAI,
The EH KT88 will sound more dynamic, tighter more powerful bass, a bit brighter top & extension.
The Svetlana KT88 will have a slightly romanticized midrange, with a burnished sound, more tubeish sounding, the EH sounding less tubeish. The highs have a bit of cloudy coloration.
It amounts to a matter of taste and the gear it is in. If the Premier 11a sounds lush with the stock Svetlana 6550 (which are leaner & more analytical than the Svet KT88), you might prefer the EH KT88.
By the way, I had both old winged C Svets, and didn't hear a difference between the New Sensor Svetlana and the winged C, and they looked identical in construction.