Ghusl counts as wudu if this ghusl was required in order to remove major impurity as in the case of janabah or following menses or nifas.

Maniy is pure and it is not essential to wash it from your clothes, but you must do Ghusl after it is emitted. Madhiy is impure and must be washed off if it gets onto the body. Madhiy invalidates Wudu' but it does not require Ghusl. Moisture is pure and it need not be washed off, but it invalidates Wudu'.

-A shower will count as a Ghusl if water reaches all parts of the body, including between the thighs, and if the mouth and nose are rinsed. -Washing each body part once is sufficient in Wudu, but three times is more perfect.