What's the difference: HM-10 and AT-09 - Bluetooth modules

Projects Networking, Protocols, and Devices
1

Hi,

I wonder if anyone knows what the differences between the modules: HM-10 and AT-09 ?

Here is a reference

But it shows only the pictures, I wish to know why choose one over the other.

My project is using an Android App with several buttons that sends commands to the arduino via Bluetooth (currently using the HC-05 which IOS doesn't support)

At times the Arduino sends some information back to the mobile device.

I'm not sure which module is better, the AT-09 is much cheaper BTW

Would love to hear your thoughts, thanks.