Dear zygospore is formed in zygomycetes and it is thick walled zygote. Oospore is formed in oomycetes and it is a thin walled zygote.

What does zygospore mean?

: a thick-walled spore of some algae and fungi that is formed by union of two similar sexual cells, usually serves as a resting spore, and produces the sporophytic phase.

How is an oospore formed?

Oospores and zygospores are the result of sexual reproduction in the Oomycota and Zygomycota, respectively. An oospore forms when an oogonium (female gamete) is fertilized by an antheridial (male gamete) nucleus; a characteristically thick wall and food reserves help to ensure survival.