The scope of this research is to compare performance of two main methods of feedback linearization of plants with internal dynamics for the problem of a two-wheeled balancing robot control. The considered methods of linearization include: 1) approximate feedback linearization; 2) partial feedback linearization with stability assessment of the plant internal dynamics using Lyapunov approach. In this case, considering both algorithms, pseudo-control signal value is calculated by an optimal state controller (linear quadratic-LQ-regulator). Experiments with the synthesized nonlinear controllers are conducted using the plant mathematical model in Simulink and the real LEGO EV3 balancing robot. Experiments demonstrate the performance efficacy and the effectiveness of both methods of feedback linearization of the plant under consideration. Taking into consideration that the aim of the future research is to develop an adaptive controller for the robot, the approximate linearization method is chosen as the basis of such regulator, since the partial linearization approach potentially increases its dimension.