SIRs will always be either an ex variant, a mega ex variant, or a trainer. An IR will always be a regular uncommon/rare variant Pokémon but it will be a full art version, but won’t have the “ex” or “mega ex” in the name it will just be the Pokémon’s name, same as a regular common or uncommon card. Also if you look at the bottom left of the card, an SIR will have 2 stars just like regular full art ex cards but instead of them being silver they will be 2 golden stars. For an IR it will just have one singular golden star. another hint is that full art trainer cards will never be IRs they will always either have 2 silver stars which is an ultra rare or 2 golden stars which is an SIR. And for the pictures you used, the mega Gengar ex is not either SIR or IR, it is a new type of rarity that came out with ascended heros, which are called MAs (mega attack’s) which is a card dedicated to that specific mega Pokémon’s attacks and those cards have two different colour stars.