I think the OP is probably asking about Tukan vs the later Kan models. Other than the name there is no mechanical or componentry link between the 1980s Kan and Kan II and the post Tukan versions of the Kan 3/4/5. The later Kan is more like a standmount version of the Keosa and uses the same drive units (but one less mid-bass driver than the Keosa of course).
The Tukan is a very solidly built little speaker and that's reflected in the sound - its pretty impressive for such a little box. The ceramic tweeter 015/1, 015/2 or 015/3 is shared with Keilidh, Kaber and Keltik and can be a bit grainy / gritty and this can get worse over time as the driver units themselves can become fragile with age. This is easily sorted by replacing them with the later 038/1 tweeter from the Katan / Ninka era and these are available brand new from Linn dealers at around £80 a pair - they're a mechanical direct fit and its just an unsolder / solder job to fit them. No changes to the crossover. Going active with the Tukan brings a step change in their capability and is worth doing - the AV5125 one box 5 channel power amp is and ideal space efficient way of doing this. The Tukans really benefit from a very solid (sand filled) stand.
I can't say much about the later Kans though, other than they were related to the Keosa which was very unpopular. I heard one pair of "modern" Kans once on the end of a Majik-I playing CDs and to me the system sounded lightweight - no body or depth and definitely sounded like a step backwards from the Tukan. Only my opinion of course, and it was a long time ago!
Tukan
Kan 3
Kan 4 / 5