Large jets are usually safer than small private planes, and private planes are normally safer than helicopters. Some of the reasons that helicopters are more dangerous and are often the subject of personal injury lawsuits are:
Helicopters naturally fly at lower altitudes when the airspace may have more obstructions that can lead to a crash.
Helicopters can land in spots that are not accessible to a regular aircraft, thereby increasing crash risk.
Helicopters feature more moving parts than an airplane, which can lead to a higher number of malfunctions.
Helicopters are more challenging to fly than an airplane, particularly for the novice.