So I've been looking to incorporate Bluetooth at some point and i've seen multiple bluetooth modules.

Things like the HC-05/06 (Which from my understanding is actually a bluetooth serial adapter), then there are the newer BLE 4.0 modules. Which seem to be either SPI/Serial.

But i've seen examples that ALSO use Nordics SDK and are super confusing to a beginner like me. Is that what the "true" bluetooth is?

I guess what im trying to figure out is how someone in "the industry" would interact with bluetooth? I see some that interact via AT command set (Which im not familiar with).

Can someone straighten this out for me? Thanks!