In this work, the effect of distributor type on fluidized bed hydrodynamics was studied by taking into account time, frequency, and state space domains. For this purpose, pressure fluctuations were measured in a fluidized bed with 0.15 m diameter and the experiments were carried out for three different types of distributors (perforated plate, bubble cap, and porous plate) at different sizes and various superficial gas velocities and particle sizes. Time domain analysis demonstrated that while the initial bubble size on the bubble cap distributor is greater than that on the perforated plate, the standard deviation of pressure fluctuations is greatest in a bed equipped with the porous plate, followed by the perforated plate and then the bubble cap distributor. Based on the current analysis and in view of the frequency domain analysis, it was found that the contribution of finer structures (small bubbles and clusters) is highest for a porous plate, followed by a bubble cap and then a perforated plate distributor. Also, according to the S-statistic method, it was concluded that the S-test is a reliable method for detection of differences between hydrodynamic situations of fluidized beds, while different types of distributors were used.