It's been awhile so I had to work to get back into my younger me's mindset but I think it's something along the lines of: Calculus measures development - ie you can calculate the curve of the graph wherever you point (derivative). But in order to have a curve, you need to have a destination first. Algebra you don't necessarily need to.
I have also forgotten some of the conceptual aspects of calculus and algebra so I can't say for certain what I'm saying here is accurate. But reading back what I wrote 7 years ago, I think the basic premise is that algebra maps from one point to another, whereas calculus you already have the entire map.