Correct. Compare the two fish in my post. One is a scomb and the other is a tat. The tat is almost identical to an armatus except for what you listed and their maximum size (18" for a tat, 3' for an armatus; neither is likely to get to their max size in an aquarium). Scombs have a completely different body shape and fins that are often green or brown near the base and clear at the end. Scombs will have a rounded tail, tats and armies have a trident tail (reference the pics). Tats and armies will be silvery or slightly golden through the body, scombs will be more of a slate grey.
Hope this helps.
