"真的" can be used in circumstances below: 1\to claim something is real or true(oppose to fake or false) 这个东西是真的adj.。2\to strengthen your attitude 这句话我真的读不懂adv.。
“确实” is often used when you wanna declare or state something. 这确实是我不对（It's actually my fault.）In this way, “确实” means "something is what it should be"(idk whether it's a correct expression). We usually use "确实" to express that we agree on some opinion and to emphasize how something works.
I'm not sure whether my explanation is precise enough. If you have any question, plz let me know. I'll try to make a further clarification.