The CK appear a bigger machine. Are the also heavier duty. With the CS I would probably get the belly mower
To help give you an idea, the Kioti CK could be compared to your 2200lb Hew Holland TC30. The CS is to small to be in that same category.
Comparing both the 25hp versions of the CS and CK are as follows:
CS2510 ~1500lbs,
SL2410 Loader lift at pins: 675lbs
SB2410L backhoe digging force: 2100lbs
CK2510 ~2300lbs.
KL2510 Loader lift at pins: 1092lbs
KB2465 backhoe digging force: 2817lbs
The CK is a heavier duty machine than the CS all around. The CK also offers the drive-over mid mounted mower, where the CS does not.
Sitting on them both, the CS feels like a large lawnmower, the CK feels like a small tractor.
Both great machines, all depends on your needs.