The meaning varies slightly depending on both intonation and position of the particle. The nuances are however not perceived by native speakers themselves.
By and large, the enclitic put into hierachial commentary on the sentence topic places the following part of the sentence into conditional modality, e. g.
Он сказал бы. (a conditional ellipsis with a reference to smth said earlier).
Он бы сказал. (an emphasis on conditionality of the action).
Сказал бы он. (the actor emphasised).
Сказал он бы. (an ellipsis / incomplete phrase).
Мы бы хотели. (the action is emphasised as conditional).
Мы хотели бы. (an ellipsis / incomplete phrase).
Хотели бы мы. (the actors are emphasised).
Хотели мы бы. (an ellipsis / incomplete phrase).
In a final position, the particle can provide conditional modality for the preceding phrase as well.