Yes, diploma engineering students from the SBTE board can appear for JEE Mains and Advanced. However, while they can take JEE Mains, they are not eligible for NIT, IIIT, or CFTI admissions through it. They can attempt JEE Advanced but will not receive a JEE Mains rank. If they clear JEE Advanced, they can apply for IIT admissions in the second year of a B.Tech program. It is advisable to review the official NTA and JEE Advanced guidelines for the latest eligibility criteria before applying.