OHV, OHC or SOHC & DOHC ENGINES.

OHV ENGINES:
OHV means OverHead Valve - an engine design where the camshaft is installed inside the engine block and valves are operated through lifters, pushrods and rocker arms (an OHV engine also known as "Pushrod" engine). Although an OHV design is a bit outdated, it has been successfully used for decades. An OHV engine is very simple, has more compact size and proven to be durable.
Downsides: it's difficult to precisely control the valve timing at high rpm due to higher inertia caused by larger amount of valve train components (lifter-pushrod-rocker arm). Also it's very difficult to install more than 2 valves per cylinder or implement some latest technologies such as Variable Valve Timing.
NOTE: this sort of engines were used in charades of 78-86.

OHC or SOHC ENGINES:
OverHead Cam while SOHC means Single OverHead Cam.
Both are same in technology.The advantage is that valves are operated almost directly by the camshaft - easy to achieve the perfect timing at high rpm. Also it's possible to install three or four valves per cylinder
The disadvantage - an OHC engine requires a timing belt or chain with related components - more complex and more expensive design.

NOTE: This sort of engine is normally used in today's affordable cars such as Cuore and Alto.

DOHC ENGINES:
DOHC or Double OverHead Cam - the setup used in many today's cars. Since it's possible to install multiple valves per cylinder and place intake valves on the opposite side from exhaust vales, DOHC engine can "breath" better meaning that it can produce more horsepowers with smaller engine volume. Compare: The 0.7-liter(660cc) DOHC engine of Daihatsu Cuore or Mira has 42.55 KW power while the 0.85(850cc)-liter OHC engine of Pakistani Cuore.
Pros: High efficiency, possible to install multiple valves per cylinder and adopt variable timing.
Cons: More complex and more expensive

NOTE: This sort of engines is used in Civics and corollas.
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Note: The animation of engines is taken from http://www.samarins.com and are not for publicity but for information only.
http://cache.pakwheels.com/forums/2007/9/23/ohv_engine(charade_84-86)_R5J_PakWheels(com).gif

http://cache.pakwheels.com/forums/2007/9/23/dohc(cultus_efi)_K6I_PakWheels(com).gif

http://cache.pakwheels.com/forums/2007/9/23/sohc_engine(suzuki_alto)_YLY_PakWheels(com).gif