Conventional is a traditional way of doing something. Non conventional is doing something in away that is not traditional. For example students going into school and being given a curriculum is a conventional way of teaching. Homeschooling students and letting them choose what they want to learn is non conventional.

Many believe that projected energy weapons will make conventional weapons obsolete.

Conventional ovens cook food much slower than microwaves.

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There are a number of conventional protein sources which mainly involve plants and animals. Some of the best protein sources include eggs, beans, white meat and so much more.