There are two types of rotorhead designs commonly used on R/C helicopters:
Flapping head (technically a fully articulated rotor head)
Seesaw head (technically a semi-rigid rotor head)
A flapping head allows each rotor blade to flap, lead/lag, and feather independently. This is accomplished by having having three hinges per blade:
flapping hinge, which allows each blade to flap (move vertically)
lead/lag hinge, which allows the blade to lead and lag (move horizonally)
feathering shaft, which allow the blade to feather (rotate along long axis)
This is typically used on helicopters with more than two blades, but some two-bladed helis such as the Corona use this.
A seesaw head typically has the blade grips for two blades connected by a feathering shaft. This feathering is rigid and only allows the two blades to seesaw as a single unit, e.g. when one blade rises, the other is forced to sink. The two blades will still feather and lead/lag independently, however.
Most R/C helicopters use this system, including the ECO 8, Logo 10, Shogun, T-rex, etc.