For the avoidance of any doubt, these are the Aircrew Regulation requirements:
FCL.710 Class and type ratings — variants
(a) In order to extend his/her privileges to another variant of aircraft within one class or type rating, the pilot shall undertake differences or familiarisation training. In the case of variants within a type rating, the differences or familiarisation training shall include the relevant elements defined in the operational suitability data established in accordance with Part-21.
(b) If the variant has not been flown within a period of 2 years following the differences training, further differences training or a proficiency check in that variant shall be required to maintain the privileges, except for types or variants within the single-engine piston and TMG class ratings.
(c) The differences training shall be entered in the pilot’s logbook or equivalent record and signed by the instructor as appropriate.
GM1 FCL.710 Class and type ratings — variants. Differences and familiarisation training
(a) Differences training requires the acquisition of additional knowledge and training on an appropriate training device or the aircraft.
(b) Familiarisation training requires the acquisition of additional knowledge.