What’s the difference between an essential oil and an infused oil?

An essential Oil is a non -oily and highly fragrant Essence which is extracted from a plant by distillation and evaporates fast. An essential oil is any concentrated, hydrophobic liquid containing volatile aroma compounds from plants.
The term essential indicates that the oil carries distinctive scent of the plant, not that it is an especially important or fundamental substance

An Infused Oil is a vegetable Oil which has been infused with the fragrance of an aromatic plant by mixing the two together and heating. The resulting Oil is delicately fragrant, very greasy and does not evaporate

Essential oils are produced by steam distillation of plant material (from flowers, leaves, herbs, grasses, wood, resin berries etc), or by expression of the rind of citrus fruits. They are highly volatile & despite their name are not “oily”. They generally require specialised equipment and expertise and would be difficult to produce at home.
Infused oils are vegetable oils which are infusedwith plant material. The plant material is heated gently in the carrier oil until the volatile components infuse into it. This method can be used for any aromatic plant but at a commercial level is usually reserved for plants which cannot be distilled.
You can try producing an infused oil at home – Fill a large jar with flowers or herbs (use ones with a fairly strong scent). Fill the jar with a bland vegetable oil such as sunflower or grapeseed. Seal the jar and place it in the sun for a few weeks, shaking it every few days. Then strain and use as a massage or body oil.