In what way is the electronic configuration of the transition elements different from that of the non-transition elements?

Transition elements have incomplete penultimate d-orbitals while penultimate orbitals of representative elements (s- and p-block elements) are completely filled up. The general valence shell configuration of s-block (group 1 and 2) elements is ns^1–2 and for p-block elements (group 13 to 18) is ns² np^1–6. The valence shell configuration of transition elements can be written as (n–1)d^1–9 ns^1–2.