The DWP are very insistent that (PIP) medical assessments are very different to Work Capability Assessment, which is used to determine if someone receiving ESA or UC is capable or work and/or work-related activity.
It is certainly true that the criteria for the two benefits are very different, but you may find the assessment process and some of the questions you are asked quite similar. Sometimes ESA medical reports are used as evidence when looking at PIP claims. If this happens to you and you disagree with the decision on your PIP claim, it is important to argue that the legal tests are different.
Current indications are that the Government intends to scrap the Work Capability Assessment and link ESA/UC assessments more closely to PIP from 2028. However, specific details of how this will operate are not yet clear.