No different things with different functions are better than the other if they are used at the right time and at the right place. In fact, proper usage bring them to their peak performance. For fire pits and outdoor heaters, though they have the same primary purpose that is to give heat for warmth during cold weather, they are made for different situations. You may feel the difference in heat generation but this factor doesn't make the other better in a general sense. Modern patio heaters are made not just for comfort but also for outdoor décor and setup enhancement to enjoy the outdoor space's purpose.
Having said that fire pits and outdoor heaters are equally good, let us know the benefits and where they are applicable to get it to its best.
Fire pits including fire bowls allow us to enjoy warmth in an outdoor place much like the traditional way. This way you can enjoy the warmth and the view of dancing real flame. Depending on fuel you use, you can also smell some warm aroma that adds to the outdoor air. This type of heating is suitable for outdoors with large open area and without close roofing. If you love to spend relaxing at night, this heater can give you a satisfying leisure time. With the darkness of the night, its blazing fire will keep you comfortable and thrilled through the night. But do not use this under or near a patio umbrella, the flame may damage it. An electric patio heater will be a better option that can be safely paired with an outdoor umbrella.
Outdoor heaters are best for convenience and for the times that you only need warmth. Available in gas and electric-powered, these heaters can give warmth with less hassle. Some may have flame effects but not much like real. This doesn't matter much if all you need a safe-and-sound warmth. This type of heaters will do good in any outdoor setup even in an open area but be sure to store and secure them after using. This heater is machine operated so it needs some protection from outdoor elements that could damage the mechanism.
The choice between these types is yours to decide. Just base your preference on how you want to enjoy outdoors and what type of environment you'll be going to use it. Good luck!