Recreational Vehicles (RV) are generally divided into two major classes or RV Types. Motorized and Non-Motorized. This is a pretty good classification because decisions between the two classes have pretty big impacts on price, flexibility, maintenance costs, and overall complexity of the RV.
If you have a pickup or SUV of any type you might lean towards a towable because you wouldn't need to purchase two engines (one in the RV and one in your pickup/SUV).
If you are starting from ground zero, then you might pick between the two classes equally.
One of the BIGGEST decision factors on picking between the RV types is deciding on how you will get around when the RV is parked and you want to drive to a nearby restaurant or fun local attraction. If you don't mind a F350 Dually as your everyday vehicle, a towable is just fine. If you want to tool around in a smart car, you probably should consider a motorized RV.
Notes on RV Axles and weights
Most RVs now have 4 wheels on two axles. The smallest campers form a class called camping trailers and they have a single axle, but most have 4 wheels. There are a few “beasts” that have 6 wheels and 3 axes – they usually fall into classes of RVs called Toy Haulers and Luxury Fifth Wheels. Almost without exception, the 6 wheels beasts are fifth wheels due to the many benefits of the fifth wheel connection.
The most important thing about the wheels that you can think about isn't really the wheels, but instead, is how the wheels and axles translate into the hauling capacities of the RV.
For example, if you look at the GVWR and the UVW you need to think LONG AND HARD about how much stuff you will put inside the RV. For example, if your RV has a hauling capacity of 500 pounds ( GVWR minus UVW ) and it is a fairly large RV ( perhaps longer than 26 feet ) then it will be VERY easy to exceed that weight limit with just clothes, kitchen items & supplies. If you put fresh water in the tank and you are overweight.
So the wheels are a KEY component ( actually it is the axle & support system too ) of the carrying capacity. So I'm encouraging you as a reader to focus on what you plan on putting into the RV. When you look at weight ratings for the RV, you might RECONSIDER purchasing a unit that has very little extra capacity.
One more note on weight capacity. If you exceed it, you could get a ticket. You could also have an accident as the weight ratings are designed to protect people.
This RV type always requires another vehicle to tow the RV.
Towable RV sizes exist in a small enough size such that a small car like a Honda can tow it, all the way up to an RV so large it requires a Ford F350 Diesel or larger.
By far... this is the most popular and most purchased variant of RV that is manufactured today as measured by the number of units sold.
Whenever you watch movies, you will see the typical Class A RV depicted.
All of these RV types have an engine installed in the RV and requires no other vehicle to move the RV.
As a special note, you will see that most serious RVers who have motorhomes, also tow a small car as large RVs are impractical for exploring and navigating as a daily vehicle.