In vitro studies are conducted using components of an organism that have been isolated from their usual biological surroundings, such as microorganisms, cells, or biological molecules.
In PubMed, you can search for in vitro articles using the MeSH term In Vitro Techniques.
Animal research is testing on animals and is considered in vivo research, or in the living. Research on animals falls under the guidance of the Institutional Animal Use and Care Committees and their guidance - https://www.nal.usda.gov/awic/institutional-animal-care-and-use-committees.
Clinical research is also in vivo testing. A clinical trial involves research participants. It follows a pre-defined plan or protocol to evaluate the effects of a medical or behavioral intervention on health outcomes. By taking part in clinical trials, participants not only play a more active role in their own health care, but they also can access experimental treatments and help others by contributing to medical research. (NLM)
The NIH has resources to understand clinical trials - https://www.nih.gov/health-information/nih-clinical-research-trials-you/basics