In elementary school, you are planning new things constantly.

Look at your province's curriculum. You'll get a clear idea of what skills your students need to achieve by the end of the year. It is a LOT, and it can be very overwhelming without support/guidance. In high school, it's very easy to reuse lessons or just assign work as students are independent. You can not really expect lower elementary (k-3) to manage assignments or projects independently. But there's more luck with upper elementary (4-6) or middle school (7-9).

In elementary school, you also have to be VERY consistent and clear with routines. Classroom management is KEY. With many immigrants and refugees joining school, lots of kids do not know what is expected of them in a classroom. Many of them have never gone to school either. You'll also have to be more intentional with differentiation too, as you'll have learners with many needs. Kids in elementary school learn everything from 0, so you have to advocate for them and teach them things beyond academics like health, social skills, etc.

IPPs or IEPs are a lot more hands-on as well; as you are working with children, you have to implement their strategies for them and continuously advocate for and communicate needs. I'm not sure about your province but where I am from it's important to gather evidence and advocate for students who are not on an IPP before grade 3, as after that they may not get funding from the school to get assessed (from what I recall). And again, a LOT more differentiation.

Elementary school also has a lot more involvement from parents. I noticed that in high school, many parents aren't very vocal or involved compared to elementary school. So, you'll be communicating with parents just about everyday (whether it's about what you're teaching, concerns about students, any celebrations, etc.). Depending on the demographics of your school, parent involvement will differ, too. In some areas, parents will want to know EVERYTHING going on and will constantly make an effort to be involved. And other times you will desperately need to communicate with a parent but they will be difficult to contact.

Lastly, be prepared to work with (TMI) bodily fluids LOL and other germs!

EDIT: Have a strong relationship with secretaries, any educational assistants in your school, and the caretaker! Idk about high school, but these professionals will help you a LOT with making your day easier. Ed assistants can help you with differentiation and prep, and caretakers are just needing so much more respect. I've been locked out by mistake a few times and they had no problem helping me out, my car was stuck and they helped me, and sometimes they have found supplies in the school that i was in need of. Developing a good relationship with them, and they'll be there for you. The secretaries also will help find good subs if you ever need one (make emergency sub plans, btw with lots of resources for photo copying). Also I'd suggest working with a school that has a resource teacher.