This paper presents a comparative dynamic analysis of two pantograph mechanisms proposed for integration into lower limb rehabilitation exoskeletons. Both configurations—a classical parallel pantograph and a Chebîşev Lambda-type variant—were modeled in 3D and simulated in MSC.ADAMS to evaluate the kinematic behavior of the hip and knee joints during walking. The models are actuated by a single motor, designed to transmit coordinated and biomechanically relevant motion. The results highlight differences in angular amplitude, motion continuity, and the fidelity of the generated trajectories compared to physiological gait. Conclusions indicate that the pantograph mechanism with centralized actuation provides more symmetric trajectories and human-like joint behavior, making it suitable for use in active rehabilitation systems. This study supports the optimal selection of mechanical architectures based on clinical requirements and the desired level of assistance.