Are nuclear medicine and radiotherapy the same? if there is any difference, then please share.

No: Nuclear medicine uses radioactive materials primarily to diagnose illness. Radiotherapy is the treatment of illness with radioactivity. There is a small area of overlap in that nuclear medicine uses radioactive iodine to treat thyroid disease (thyroid overactivity and thyroid cancer) and rarely treats the bone pain of metatastases with radioactivity. Otherwise is entirely used to diagnose.

No, but overlaps: Nuclear medicine is primarily diagnostic where we inject patients with a small amount of radioactivity and take a picture. However, in some cases, we administer patients with larger doses of radioactivity to treat select diseases. Radiotherapy treats patients with external beam radiation instead of injecting them or given it orally, but some rt docs also do the nuclear medicine therapies.

Not exactly: Nuclear medicine uses isotopes mainly for functional diagnoses of disorders of gall bladder, heart, brain, lungs, thyroid,bones, kidneys and bladder. Nuclear medicine has a few therapeutic uses including thyroid ablation and therapy for prostate bone metastases. Radiotherapy can involve radiation therapy with xray and proton beams, not considered part of nuclear medicine.