There are several good professional grade airless paint sprayers out there at reasonable prices. The base unit is the airless pump and the different nozzles used in the sprayer head make the difference in the style of application. The spray pattern and volume the nozzle allows as well as the types of paint or stain it can handle determines how it can be used on different projects.
I for example have a Graco Pro LTS17. I have a variety of tips that range from 14 inch wide high volume which makes shooting out a house a one day job, down to much finer spray tips that shoot properly thinned cabinet enamels in very tight patterns. One of the advantages of this type of pump sprayer is that you can feed product directly from a 1 gal or 5 gal can.
As with all sprayers, using the right paints/stains for the job and thinning them with Flotrol for latex or mineral spirits/linseed for certain oil based products makes all the difference on how the sprayer preforms and how well the product covers.
i kick myself for not having used one years ago. Once I started using mine a few years back, projects for painting a house exterior, decks with hundreds of spindles, priming new construction drywall, and refinishing wood cabinets became so much easier, faster and with not that much practice, a very nice finish.
Don't go cheap. Be sure whatever unit you buy is versatile and accepts all the tips you need for your varied projects.