While there are some similarities, there are a few fundamental differences. 

1. The INTI was designed to be driven safely on the road so it has safety features such as a full roll cage, side-impact bars, three-point seatbelts, head restraints and regulation front and rear bumpers. Golf carts are designed to be driven on golf courses, so these safety features are absent. Although golf carts can be made road legal with the addition of lights and mirrors, without these built-in safety features they are not as safe as the INTI. 
2. The INTI was designed to be fully solar powered, it is therefore a foot wider than a golf cart which allows it to absorb more solar energy. Golf carts were not designed to be solar powered, their roofs are too narrow to collect meaningful amounts of solar energy. 
3. Because the INTI is solar powered, it was designed to be parked outside to catch the sun. Golf carts are not designed to be kept outdoors and are usually parked in garages where there is no sunshine (incidentally, this feature of the INTI can free up a lot of space in your garage!)

Although the INTI is not a golf cart, it is lighter than most golf carts and can be fitted with turf tires and a golf bag holder making it suitable for use on golf courses.