Difference will be there, as both the entities are sharing the same node which means that the relative stiffness of both the entities will be considered while sharing the proportion of vertical reaction.
For example, remove the self-weight (as the loading will vary while changing the thickness) and apply a certain plate pressure loads on the plate (say -1 N/mm^2). Now, create three models with different plate thickness ( 1000 mm , 100 mm , 1 mm). Now run the models separately and see the "Fy" value of the beam end . You would notice that the model with the thickest plate will have least beam end force and the vice versa which manifests that the force distribution is related to the relative stiffness of two entities connected at the same node.
For example, remove the self-weight (as the loading will vary while changing the thickness) and apply a certain plate pressure loads on the plate (say -1 N/mm^2). Now, create three models with different plate thickness ( 1000 mm , 100 mm , 1 mm). Now run the models separately and see the "Fy" value of the beam end . You would notice that the model with the thickest plate will have least beam end force and the vice versa which manifests that the force distribution is related to the relative stiffness of two entities connected at the same node.