A BLE scan response is the packet that is sent by the advertising device (peripheral) upon the reception of scanning requests (i.e. yes, it is a response to a device scan). The scan response usually has more data than the advertising packets. In other words, central devices send scan requests to the advertising device in order to get additional user data through the scan response. Please also note that scan responses are considered to have fixed 'static' data relative to the more dynamic advertising data.

Advertising packets and scan response share the same format, and are transmitted over the same three physical channels (they are both sent as advertising events), but are otherwise two different things.

For more information, I recommend reading about scan response packets in the SIG's core specification found here.

The scan response packet consists of: Device name, Transmission power, Beacon ID, Firmware version, Battery level.