There are a few main differences between a commercial and infomercial, firstly an infomercial is far longer than a normal ad.
Usually ads are around 15 to 30 seconds long and are on every time slot of the day on television. Infomercials are up to half an hour long and are usually on day time tv when mothers are at home so they can buy the products. 

Another difference is the aim of the ad, infomercials show every aspect of the product and only certain products are shown. For example, usually objects like food or consumable objects. Other things that may not be consumable but aren't put on infomercials are things like insurance and cars.

The objects that are mostly on infomercials are everyday house hold objects or things that cant easily be advertised in a short space of 15 to 30 seconds. Most gym equipment is advertised on infomercials because the product needs to explain itself to the consumer. Also kitchen utensils and vacuum cleaners are ofter advertised during the day because they are products targeted towards middle aged stay at home mums. This demographic is usually short on money, with a lot of time on their hands. The product being sold needs to be explained to them in detail in order to convince them to buy it because they are usually hesitant. 

This contrasts with the purpose of the average ad, that tries to get you to buy a product or service in just 30 seconds, so only a snippet of the product is explained or shown. This is targeted at different demographics and attempts to catch your attention instead of a long description and demonstration of the product.

Infomercials are often over looked because of their cheesy exterior and cliche nature, but it is targeted towards a certain type of people and is de