The GHS was implemented through Community legislation in the form of Regulation (EC) No. 1272/2008 on classification, labelling and packaging of substances and mixtures (CLP Regulation) which is legally binding and directly applicable in the Member States of the EU, whereas GHS is not legally binding.
GHS and CLP are not identical because CLP is also based on the old EU legislation on classification and labelling, i.e. the Dangerous Substances Directive 67/548/EEC (DSD) and the Dangerous Preparations Directive 1999/45/EC (DPD).
In addition, and based on the so-called UN GHS "building block approach", CLP does not include all the hazard categories included for a hazard class because they were not part of DSD, e.g. category 4 of the hazard class flammable liquids, or category 3 (mild irritant) of the hazard class skin corrosion/irritation. CLP includes special labelling and packaging rules that are not part of the UN GHS, but which were brought over from the DSD and DPD, e.g. the rules on small packaging (CLP Article 29), on supplemental information for certain mixtures (Part 2 of Annex II to CLP) and for the provision of child-resistant fastenings or tactile warnings. Also, it includes rules for the situation when a substance is both covered by CLP and by transport legislation (CLP Article 33).
It should be noted that in contrast to the UN GHS, CLP does not include specific rules on Safety Data Sheets as they are already regulated by REACH, through its Article 31 and Annex II.