In valvate aestivation the the whorls are just fused but in imbricate the overlap each other but not in a perticular direction genrally one is completely inside one is outside and the other 3 are twisted...

And imbricate corolla aestivation.

Valvate corolla aestivation refers to a floral arrangement in which the corolla lobes or petals in a flower bud are touching each other at the margins but do not overlap. When the flower bud opens, the corolla lobes separate and spread out, similar to the opening of a valve. This arrangement can be seen in flowers like morning glory (Ipomoea) and phlox.

Imbricate corolla aestivation, on the other hand, refers to a floral arrangement in which the corolla lobes or petals in a flower bud overlap each other at the margins. The overlapping pattern is similar to the way shingles or tiles are arranged on a roof. When the flower bud opens, the corolla lobes unfold or untwist in a specific sequence, with one lobe usually emerging first, followed by the others. This arrangement can be seen in flowers like roses (Rosa) and primroses (Primula).

In summary, valvate corolla aestivation involves corolla lobes touching each other without overlapping, while imbricate corolla aestivation involves corolla lobes overlapping each other in a specific sequence.