Development Length is essentially provided to create a bond between steel and concrete in order to transfer the bar force without slip to prevent the bar from pulling out under tension.
Image A: The development length is provided in the beam and column junction. Due to this the stresses developed are easily transferred by the bond created by steel and concrete.
Image B: The development length is not provided in the beam and column junction. Due to this the stresses developed in the beams will not be able to transfer it to the column.