The probability distribution is different owing to the way it is calculated. Like mentioned in few posts above, as long as you keep multi_class = False, the softmax is calculated across the scores coming in entailment for all the classes. Whereas when not using the pipeline the way softmax is calculated would be different.
The speed variations seem interesting. Could you please share some numbers associated and the specifications of the machine you’re using for it?
Hope this answer made sense.@kmehra