Lists identified by El-Guest and we can say the things with the property
have a different number of syllables than the other elements in their sets.
7 and not 6
7 has two syllables while the other numbers 1 to 10 have one.
W has three syllables while the other letters in the alphabet have one.
Spring and not Autumn
Spring has one syllable while the other seasons Summer, Autumn and Winter have two.
Yellow not Blue
The primary colors of pigment are simplified as red, yellow and blue: yellow has two.
Rock not paper
Rock has one while paper and scissors have two.
The secondary colours of light are magenta, yellow and cyan: magenta has three.
Gas not solid
Gas has one while other states of matter, liquid and solid (even plasma) have two.
Thanks to El-Guest for this: Head, Shoulders, Knees, and Toes: Shoulders have two.
Medium has two while small and large have one.