Thunderbolt port not charging smartphone

I have Dell Inspiron 15 - 7577 with thunderbolt (usb-c) port. I connect my smartphone [Motorola One Vision] with usb-c>usb-c cable but can only send files. Phone is not charging battery with that port. Second qestion is that why there's no difference in speed when I send files with that 2 options [Laptop - Smartphone]: 1. USB-C > USB-C 2. USB-3> USB-C Regards, Przemek