1 Both can produce silk
Both male and female spiders can produce silk and create webs.
2 Females are the ones who usually build webs
It is generally accepted in the arachnological literature that adult female spiders build typical webs, while adult males do no web-building other than that required for courtship and sperm induction.
3 Adult males don't build webs
juvenile Male spiders build webs but when they grow up they usually stop.
4 Spiders seen in webs are usually female
The spiders seen living in a web are more likely to be female spiders.
5 Females build more significant webs
While male spiders sometimes build webs, their webs are still less complex and usually smaller than that of a female spider. The full webs people see around are usually built by female spiders. See why many people find insects disgusting.
6 Males build webs for mating
Male spiders build webs primarily for mating purposes. Male spiders build webs and pour their semen on it when they want to mate with a female.
7 Male spiders abandon webs
While the female spider usually lives in or around the web, the male spider abandons the web and starts searching for a new female to mate with. This is why female spiders are usually noticed on webs.
8 Some males use female webs to eat
Some male spiders use the webs already built by females to eat. Those spiders eat from the preys caught by the female spider's web.