A couple of the biggest indicators that can help narrow down male ekkie subspecies are:
1. Weight and length
2. the presence or absence of a green stripe along the primary feathers. Here is a photo of my red sided males primary:
3. The hue of the green feathers. It's not always easy to notice, except maybe in sunlight. The two colors are a darker forest green, and a lime/grass green. The difference is very subtle.
The red color is simply a random mutation, and atypical for this species. Not common at all but kinda cool.
Not knowing how your guy fits in to the key above based on your two photos, if you are located in the US the likely answer would be either a Solomons Island (smaller of the subspecies), Vosmaeri (larger, no green stripe on primary), or red sided (larger, with green stripe on primary).
Congratulations on your new ekkie! Make sure you read up on their diet. You can't get away with just seed based diet, and not too many pellets. Mostly fresh fruit/veg/grains, with emphasis on vitamin A and higher fiber.