Some of the features that differentiate different types of hose fittings are:
Flareless - These types of fittings consist of a ferrule body that tightens on to the fitting nut and compresses the tube in a way that it penetrates the outer diameter of the tube and seals it. Flareless tube type require less tube preparation and can withstand a pressure of about 3000 psi.
Elbow - these kind of hydraulic hose fittings are available in different sizes which are basically 45 degrees for both male and female along with 37 and 90 degrees. As indicated by the name of the fitting, both ends of the fitting are connected to the hose at the designated angle. Elbow is usually used in plumbing applications.
Flanges - flanges are designed for those kinds of tube fittings that are larger than an inch in size. Torque power as well as large wrenches is needed to tighten these types of fittings. Split-flange fittings differ because they generally use O-rings to seal a connection.