Hemp and cannabis are very closely related plants but the terms typically refer to very different kinds of medicine. If you are looking at hemp oil the most important piece of information is to look for CBD content (if any). For instance, hemp oil without cannabinoids might be used as a dietary supplement, but hemp oil made from CBD-producing plants can be used for medicinal purposes. Cannabis oil generally refers to oil extracted from cannabis flower, and will contain various amounts and ratios of cannabinoids like THC and CBD. That oil can then be put into various types of medical marijuana products like vaporization oil, topical creams, edibles, etc. For ulcerative colitis, most people find that using a combination of THC and CBD helps relieve symptoms of pain and inflammation.