For undergraduate courses, the comparison between IIT BHU and IIT Roorkee is kind of pointless. Since both institutes are well-reputed institutes. The faculty base and facilities offered to students for undergraduate courses are almost similar. The required cutoff for admission at both institutes is almost the same.
Although in terms of placement IIT BHU is a little ahead of IIT Roorkee.
Both IIT-BHU and IIT-Roorkee are good institutes and your GPA, recommendations, and projects are more important for higher studies rather than the IIT name. However, when it comes to placement package, IIT-BHU is certainly the better option. There are a lot more companies with lucrative packages visiting the BHU campus for placement drive as compared to IIT Roorkee. For example, if you take HUL which has an internship program named ULIP, pays about 1 lakh /month. Moreover, if you are lucky enough to receive a pre-placement offer, you get a lump sum package of 24 lakhs/annum. HUL only visits 6 IITs including IIT-BHU but not Roorkee. Due to its remote location, Roorkee has a smaller number of MNCs visiting its campus.