The fundamental difference
A static QR code stores the information itself (such as the actual URL or text) directly inside the code. Once created, the content can't be changed, but it works forever without depending on any server.
A dynamic QR code stores only a short "intermediate address" that redirects to the real destination. This lets you change the destination without reprinting the code, and you can also collect statistics such as scan counts.
Static QR: pros and cons
The advantages are clear: no expiration, no external service or subscription required, and fewer privacy or tracking concerns because there's no intermediate server.
The downside is that you can't edit the content, and a long payload makes the code denser. Every QR this site creates is a static QR, so once you make it, it keeps working with no updates needed.
Dynamic QR: pros and cons
The advantages are editable destinations and scan analytics. You can swap a campaign link without recalling printed materials, which is useful for marketing.
The downsides are that it usually requires a paid subscription, the code can die if that service shuts down, and the intermediate server tracks your scans.
Which to choose
For content that doesn't change — WiFi access, business cards, fixed information links — a static QR is the simplest and safest.
For frequently changing promotion links or marketing that genuinely needs scan analytics, consider a dynamic QR service. Once your purpose is clear, the choice is easy.