QUESTIONS:
What is the difference between an EARTHING CONTACT and an EURO CONTACT?
What do PROTECTIVE SYSTEM 1 and PROTECTIVE SYSTEM 2 stand for?

ANSWERS:  

EARTHING CONTACT:  „with earthing terminals both in the socket and at the
plug“. An earthing contact plug has 4 contacs:  2 pins for the external conductor
(pole/phase) and the neutral conductor (null) and 2 areas of contact for the
protective conductor (earth) 

EURO CONTACT:  flat plug, without earthing contact.
A Euro connector has 2 contacs: two thin pins for the external and neutral conductors, which are isolated at the beginning. The Euro connector fits into the sockets of many countries, as the distance between the holes is almost the same, only the position/form of the protective conductor varies.

Both terms are part of the VDE. The basic idea with respect to electric devices is that a defect must not be sufficient to cause a dangerous situtation. The safety devices therefore have to be redundant.

PROTECTIVE SYSTEM 1:  The earthing is connected to the enclosure.
Primarily, all active parts (current-bearing parts) are isolated according to their voltage. Additionally, all non-active parts which are conductive are connected to the protective conductor. If the isolation is damaged, the enclosure will be live,
but the voltage will be carried off to earth potential by the protective conductor.
This causes a short circuit which blows the fuses or activates the protective conductor.

All devices of the protective system 1 must be supplied with an earthing contact plug.

PROTECTIVE SYSTEM 2:  shockproof, enclosure made of electrically isolating material.

For the protective system 2, Euro connectors are sufficient.