C150's and 152's never left the factory with an increased leading edge radius wing, the 172 and others did beginning in 1974. This gives the newer 172's wing aerodynamics similar to those of a Cessna with a STOL kit cuff on it (much lower stall speed).
This benefit was never extended to the 150/152. Probably this was mostly due to the affect of this increased leading edge radius on the wing on spinning. The increased wing leading edge radius makes the plane much harder to hold into a spin. 150/152 needed the spin characteristics retained for training much more than it needed the reduced stall speed, and improved STOL characteristics. If spinning a newer 172, refer to the flight manual procedures and limitations. Do not spin STOL kitted Cessnas (as directed by a required limitations placard). Though the aircraft can be spun, the recovery can be unexpected.
Also be aware that Cessnas with the larger radius leading edge wing are very comfortable to fly at slower speeds. This is safe with power, but the safety of the lower speed is deceptive when performing a complete power off landing. Yes, the 172 tends to float, but if it is glided too slowly, it will not really have any reserve energy with which to flare, and a hard landing could result. Glide and flare at speeds as directed in the flight manual.
If you want to appreciate the difference, have a look at the leading edge of the wing of an older 172, it is noticably less radius (or "sharper"), as is the 152 wing.
If you ever have the chance to really fly and stall a STOL kitted Cessna, the difference is stellar. The STOL kit is, in my opinion, the greatest possible safety aide a Cessna could have. My STOL C150, when lightly loaded, will climb 150 FPM with full flaps, and can be banked side to side 30 degrees, while flying at 23MPH IAS. (helicopter airspeed indicator installed so as to read these low speeds, the factory one just sat on zero!)
Pilot DAR