Hemp is a strain of Cannabis sativa used mainly for its fibre. Hemp is very low in both CBD and THC compared to Cannabis. Hemp oil is low in CBD both THC, making adverse (or positive) effects from these unlikely. Quality of hemp oil is unregulated so there could be any number of contaminants or other harmful byproducts of extraction present.
Cannabis oil is produced from Cannabis sativa plants and contains both THC and CBD.CBD oil contains only the CBD active ingredient, without THC and its psychoactive effects. When manufactured legally cannabis or CBD oil should be pharmaceutical grade, tested for consistency. and labelled with the concentration of active ingredients within. Medicinal cannabis products such as CBD oil are classed as scheduled drugs in Australia and can currently only be legally used by humans if prescribed by a doctor.
Hemp (a form of very low THC cannabis) used in dog treats does not contain enough THC to cause adverse reactions and is therefore considered relatively safe. A very large amount of hemp is required to produce even small amounts of CBD, so there is unlikely to be enough CBD in hemp based pet treats to have a therapeutic effect.
Aside from CBD, hemp seeds included in pet treats can be a good source of protein and essential fatty acids, particularly omega 3 and omega 6 fatty acids. While omega fatty acids can have a whole host of benefits for pets including supporting skin and coat condition, joint function and cardiovascular health, it's important to be aware that omega fatty acids from marine sources such as fish oil or green lipped mussel powder are more readily utilised by pets than those from plant based sources such as hemp seeds or flaxseeds.