What is the difference between mortar and concrete

[anders.schippers]

Hello

I was planning to build a pizza oven according to the description here: https://www.k-rauta.se/rad-och-guider/grill/bygga-pizzaugn I wonder if I can use fireproof mortar instead of casting mixture (whatever that is)? On English sites, castable refractory cement = gjutbar eldfast cement is used. I live in Portugal so I do not have access to specific Swedish products.

 

[Tbone]

The description states that it uses cement mortar s30 as casting material... regular fine concrete would work too but might have slightly larger fractions in it...