Veganism is about not using any animal products or contributing to any industry that uses animals. Mainly because of ethical and/or ecological reasons.

Vegetarianism is about diet (mostly due to religious or health reasons) and is mainly concerned with not consuming animals themselves.

Vegetarians may eat honey and dairy, may wear leather (religious Hindus would consider leather unclean as it involves killing) but vegans would not touch any of the above as it all involves living animals in one way or another.