If you have been handed a boot where you expected a cast, it is fair to ask whether you are getting less protection. The research gives a reassuring starting point, with one thing to check.
The short answer
For recovery after ankle surgery, one review found the two options comparable. A meta-analysis of randomized controlled trials on NIH PMC concludes that overall, both braces and casts demonstrated comparable effectiveness in postoperative ankle function recovery and wound complications.
You can read the removable brace meta-analysis on PMC yourself. It compared removable braces with casts, so ask your surgeon or provider whether the boot you were given counts as that kind of brace.
Cost, skill and whether you can undo it
A removable device can be taken off, which makes it a reversible choice by design. That is also why it needs a little care from you. You are the one putting it on, so follow your provider's instructions about when it stays on and when it may come off.
Cost varies with the device and your coverage, so ask about it before you leave the office. Using a boot takes no special skill beyond following those instructions.
Questions to ask about your boot
Ask three questions at your visit. Which device is right for my injury, how long do I wear it, and when may I take it off? Cleveland Clinic's page on broken or fractured feet is a readable companion if you want background before you go.
Stop and ask a professional if the injury is a suspected break, if you are unsure whether the device fits, or if you feel worse rather than better. People in Wood Dale and the surrounding towns can raise it with a podiatrist or foot and ankle surgeon nearby.
A note for your first time in a boot
Wearing a boot or a cast is new for most people, and the questions you have are the ones nearly everyone has. Ask them early and you will feel far more in control.