From now on, all kinds of Letraset toys & promotional items are referred to as such, but this is the first & original use of the term 'Action Transfers'. All earlier product lines were referred to as 'Instant Pictures' (often 'Magic Instant Pictures'), but that expression isn't used after this — probably to avoid confusion, or perhaps even legal difficulties, regarding Polaroid products.
The obvious difference between the two ranges is that Action Transfers sets are 132mm x 195mm (5¼" x 7⅝") in their wrappers, whereas Super Action Transfers are a very much larger 223mm x 395mm (8⅞" x 15½").
Picture Credit: the SPLAT Scan Archives, with thanks to StellarX (7 Wonders)
© Tom Vinelott 2020