Hero call is tougher for me.
When I river bluff, I have some certainty after playing a few
hands with that player that it will work. I never 100% certain but Im right most of the time, with the read I get.
Hero call is really difficult cause if after playing with the player, I still not sure if he has the goods or not unless he was called in the previous hand and I could see what hands he was playing and know it was a bluff or if he shows a bluff to make apparent he`s capable of a bluff.
With new players that I never played I have with I can not assume anything