It's a long list of species-below page has some good info. to get you started.
The easiest way to answer this question is to provide a web link to a page that explains things far better than I could.
http://www.ratbehavior.org/RatSpecies.htm
Lab, Himalayan, Piny, Swiss, Hairless
Regular mouse and trackpad (laptop)
The two most common types of compressors are the positive-displacement and the velocity or dynamic.
The two most common triads are the Major and the minor triad. The other two types of triads are diminished and augmented triads.
The two most common types of the disease are Bancroftian and Malayan filariasis, both forms of lymphatic filariasis.
anticlines and synclines
O+ and A+
anticlines and synclines
rudder rudder post
The two most common types of trencher machines are the walk behind and the attachment models. They are used for digging trenches for laying pipe, cable or for trench warfare.
The two most common types of fans and blowers are the axial and the centrifugal, which together account for about 45 percent of the industry's output.
The use of long lines and different types of netsare the two most common methods of commercial fishing.
internal and external
You have been asked by your manager to conduct a preliminary search of recommending the two most common types of contemporary planning techniques - Project Management and Scenario Planning.