I hear twins are different but most siblings I've seen who are not twins seem to demonstrate this. I haven't known many sets of twins, but they seem to be siblings that are closer to picture one. I'm going to watch my friend's twins carefully. They are only toddlers now.
Twins are fascinating and in terms of psychology an rare opportunity to observe various social effects. From what I know twins or siblings close in age will compete for their parents attention. In my case my brother who is multiple years older than me just practices WWE moves on me for fun. Pity he gets annihilated in warhammer