Instance

The noun instance means an occurrence or an example.

Examples:

• This is another instance of Mark's poor behaviour.
• Take a look at his latest project for instance.

Instants

The word instants is the plural of instant, which means a moment of time.

Examples:

• The light bulb lasted no longer than a few instants.
• A couple of instants after the lightning, a deafening thunder roared above our heads.