GATE and Defence are way different exams, GATE is a good .GATE score is helpful for getting admission in to IITs, IISC, IIITs, NITs and many other renowned institutions. GATE qualification is also a minimum requirement to apply for various fellowships awarded by many Government organizations like DRDO, BARC, ISRO etc. for Defence one must appear for CDS, NDA, CRPF and other defence exams