Due to the expansion of renewable energies in the electrical grid, the number of inverter-based resources (IBR) is increasing. This leads to inverter-grid interactions which can be critical for the system stability of the grid. It can form resonance circuits together with IBRs at certain frequencies, which affects system stability. To investigate whether a resonance circuit exists at a frequency inside a system without knowledge of the detailed inverter structure, the frequency dependent impedance of a power plant as well as of the grid is required. In this paper, the frequency dependent impedances of two inverter control types are presented: A grid following inverter control and a grid forming inverter control realized as a droop control, which are each parameterized as a photovoltaic or type-4 wind power plant EMT average model. For each control type and parameterization, the frequency dependent impedance is calculated and compared for a variation of parameters and operating points. The characteristic changes due to parameter variations in the frequency dependent impedances of grid forming and grid following control are explained and compared for each type of power plant. The inverter models with a simplified primary side are also each compared to power plant models with a detailed primary side to investigate how complex power plant modelling must be to generate accurate frequency impedances.