Spike:
It is similar to raceme but the flowers are sessile e.g., callistemon (bottle brush), Achyranthes etc.
Spadix:
It is also spike with fleshy axis. The entire inflorescence is enclosed in by one or two large brightly colored bracts called the spathes. Flowers are mostly unisexual and incospicuous e.g., iberis amara (candytuft fam, cruceferae), Prunus sp (Fam rosaceae)