There are different sizes of QR codes, different versions of QR codes, different ways to encode the data, different methods of error correction, different degrees of error correction, etc., meaning the same data can produce different QR codes.

In addition, it is possible to encode more information that just the address in a QR code. One code may also include a request for payment, an amount to be sent, or even additional information which will be read by your wallet (Example: Electrum contains a "description" field which can be encoded in the QR code).

As long as the both scan to the correct address, nothing to worry about.