The schematics work in the same way, one using a Triac and the other two back-to-back SCRs. The main difference is how you trigger them, both SCRs in the same phase must be conductive at the same time but the triggering circuits between phases must be isolated from each other. How do you trigger them in the second design?
Note that in the second schematic, one phase is wired straight through, in the first it is wired through a Triac. You can simplify the first circuit by connecting L1 directly to the motor.
Brian.