Why do I get different QR codes from the same input with different QR generators?

Question

I generated 2 QR codes with 2 different generator tools but the same input data. They generated totally different looking QR codes. If I scan the codes I get the same data, so it seems OK, but I'm not sure about this phenomenon's cause. Any idea?

EDIT: Example:

The input data: HTTP:/ /IQR.HU/Q/MP00AD483FEE6AC8E82B2B6D87C16526785BF6EA28731C943171C3907761E87BC8227C816202849A9FCF174B38016C26AA93ADD4883DD0943FAF7B5E38423E1792FA8EAB6DE5B5CD1BF42A0C2A8B5F73DD0E5E48F4E4FDF3E8356E5E3537D5C677D7377347075E3745B824A78EB808A6F8F6E96A8B710ADA30AD93DF7B96CE664CE5

Answer 1

The encoding allows for a certain amount of variability in data representation. The error correction level and/or the mask pattern are probably chosen differently by different implementations. Customization may also play a role. (There are examples of QR codes which contain a pixelated image for PR reasons and still decode just fine.)