To engage in a project. To participate in a project. To contribute to/into a project. To cooperate with someone on a project. To collaborate with someone on a project. It is not possible to contribute without participating, but it is possible to participate without being engaged.

Engage : Is usually limited to communications. "The group needs to engage with the local authorities" Participate : takes a part. It is usually used in a passive sense organisation-wise. e.g. you participate in an event that someone else organised. "He participates in the events that the club organises". Contribute : to do something that benefits someone else or something else. That can be either giving money or goods, or doing work that benefits. "He likes to contribute to the work that the charity does" Cooperate : to do work that benefits both you and the others that you cooperate with. "The children cooperated to build a tree house" Collaborate : to cooperate, but usually in a more academic or creative sense. "The musicians collaborated to make this song" You can only be 'engaged'. You can't be -ed with any of the other words in your list. So, no, you can't really contribute without participating, but you would not say someone participated if they actually contributed, as that tends to suggest they didn't contribute. Does that make sense?

All these words have similar meanings, however, they are used in different instances (cases). Someone cannot be contributed, but something. In other words, we do not contribute someone- a person. We contribute something - a thing (money, clothes, etc.) The answer to your second question is: yes. Someone can participate in something ( an event ) without being engaged ( attentive/interested).