I think the difference would be its lower transaction fees than to its competitors, as stated on their FAQ. "In the future when we begin charging fees we will give all users at least 30 days notice. Our fees will be in-line with our vision to provide a cost effective solution for Merchants."
Lower fees are declared as the main advantage though no concrete figures are disclosed. Looks shady
Well, if you have looked closely to the website and to the answers I have provided here in the thread then you wouldn't be asking that question. Right now, paybear's fees are at Zero but will certainly changed after the 3 months intro period, but wouldn't be that high compared to current payment gateways right now in the market.