There is a BIG difference between the "off road" (also known as "trail") bikes and a MX bike.
A MX bike is built for race. If it doesn't help it go fast, it generally will not be on the bike. So no kickstand, no lights. The engines are built for performance and generally need premium gas. While the bike is rugged the engine requires frequent top end rebuilds.
The "off road" models are built for more casual riding. The seats are usually lower to the ground to accommodate shorter riders. This usually comes at the expense of less suspension travel, making the bikes less suitable for MX track use. The engines are "de-tuned", which means they run just fine on regular gas and will last a long time, but they won't develop the horsepower that their MX cousins will. The bikes are heavier. They generally cost a lot less, like half what a MX bike would cost.
Then there are the "enduro" / "Dual Sport" models. These bikes are generally closely related to the MX bikes, having high performance engines, full suspension travel and such with the addition of lights and a kickstand. They tend to cost a bit more than the MX bikes do.
If you are planning on riding the MX tracks then I would recommend getting a MX bike. I would much rather have a MX bike on the trails than a trail bike on the track!
If you are planning on getting a 450 you probably won't have a choice of a trail bike. the 450s are usually either MX or Dual Sport models.
Rod