What is SVG?

Not pixels but instructions - shapes, paths and text that a browser draws at whatever size you ask for. That makes it perfect for logos, icons and diagrams, and useless for photographs. Converting an SVG to any other format here is the moment it stops being able to scale.

What is BMP?

The Windows bitmap, which stores pixels raw with no compression worth mentioning. Files are enormous. It survives because it's trivial to read - if you're writing an image loader from scratch or feeding an embedded display, BMP is the format that needs no library.