The difference lies in what is inside. A security door is made of wood with one or more steel sheets inside it; an armoured door has a complete steel structure, both the leaf and the frame.
The security door is the most common type in flats and homes in the area. With a good security lock, a protected cylinder and an escutcheon, it gives a very reasonable level of protection for a home.
The armoured door is heavier and stronger, and needs a purpose made frame firmly anchored to the wall. It is seen less in homes and more where maximum protection is wanted.
We work with security doors. We do not sell armoured doors, although we do open them if you are locked out. It is all in security doors.