simple:
Gas consumption
comfort wise, they are probably the same.
Performance wise, while the Forester Turbo is fast... and I have flogged the hell out of it and enjoyed it, Im sure the CRDi Tucson will be give about 95% of the performance and even more low-end torque/grunt at much much less cost of fuel. Remember while the Forester Turbo has 230 hp vs the 200 hp of the Tucson, it has less torque. And the 230 hp is only reached at a high 6k rpm. You will get most of the grunt of the CRDi from 1k rpm until about 3k rpm. In city driving, the instant torque of a diesel (I speak from experience) makes a hell of a lot of difference. Also, the manual mode of the Forester TUrbo is next to useless as it only has 4 gears. If you will use this mode in the twisties, you will probably be shifting between 2nd and 3rd most of the time. Thats just one gear change. No fun. Just leave it on sport mode.
On the other hand, the 6 speed tranny of the Tucson will give you more choices. But thats just me. Who cares if the top speed of the Forester Turbo (about 230 kph) is more than the Tucson. When will you have the occasion to see it often enough to enjoy it?
With the Forester Turbo, everytime you floor it, you know you are burning a lot of gas. A LOT of Premium Gas. From SLEX to Tagaytay and back you will expend more than a half tank of premium gas.
Both are AWD. Both have sunroofs. Both are leather. Both have a ton of airbags. But the interior of the Forester is plain. As in boringly plain. The Tucson has more of a sense of occassion to it.
Looks wise....the Tucson also is more modern.
I dont mind saying that the Tucson CRDi premium is a better ride than my own Forester Turbo. Because it is.