First of all, you are driving in a strange, new land, in a strange new car on the wrong side of the road, so unless you are a super confident driver, no, it will not be easy to drive in Orlando.
However, dont let this put you off. To start with, you already know how to drive a car so you wont be starting from scratch. It will feel a little odd sitting and driving on the wrong side of the car, and YOU WILL, at least once during your holiday get into the passenger seat through force of habit and wonder where the steering wheel has gone.
My biggest problem on my first driving trip was getting lost. We were lucky enough to hire a villa that had easy access to the Osceola Parkway, so getting to Disney was no problem however coming home was always an adventure! Make sure that you use the maps provided by the car hire companies to plan your journeys in advance and remember that when you approach a road junction the name plates slung across the junction show you the name of the road that you are crossing, not the road you are driving on.
There are some excellent sites on the web that give fantastic advice, I am sure if you Google "driving in Orlando", or enter that in to the TA search engines it will come up with oodles of advice.
Dont worry about it, it will get easier the more you try and you will even enjoy the experience of driving in a foriegn country. Think of it like s*x, even if its bad its good!