Help understanding BLE

Good day everyone!

While the tittle of the thread is vague, I hope my question is not.

For what I've learned, Bluetooth 4.0 "Low Energy" is a protocol that efficiently exchanges small packages of data. Physically, both Classic and LE uses 2.4GHz and the same antenna, but different modulation.

Ok, considering I own 2 BLE capable devices (an ESP32 BLE and my Android phone) I decided to program them following Bluetooth Classic examples and tutorials because it's way easier to just do Bluetooth Serial for my project.

What happens next? The devices' Bluetooth chip don't use BLE and therefore are more power consuming?

According to Wikipedia, Classic is 1W while BLE is 0.01 to 0.5W.
But is it really noticeable? I mean, the data transmission will be very low (a few bytes from time to time to control some elements), but I imagine the fact that both devices are paired and connected will imply a periodic exchange of info make sure they are still that way. And in that case the BLE is way more efficient.

Thanks for your help!

The LE (Low Energy) part of BLE is in reference not to the power output when transmitting, but rather the size of the data being transferred and the length of time between transmissions. BLE does not require a periodic exchange of info to "keep connected" or to "remain paired". The client will periodically scan for a server, and if it finds one with a characteristic that it is interested in, will initiate a connect. The server will send a response. The client can then do one or more types of things.

It may just take that response and do whatever is appropriate to the client.
That might be to send a command to the server, or to do something with a peripheral.

It may connect more than once and collect the responses.
The responses might be a series of readings from a sensor, for example.

It might even tell the server to respond with a different type of response.

For a very well done treatise on the ESP32, including BLE, have a look at leanpub.com, and do a search for "kolban", which will point you to some books he has written. The books are priced from Free to whatever you wish to pay.