By Christina Cheddar Berk, News Editor at

NEW YORK ( CNBC) -- Not surprisingly, the way men and women shop online mirrors very closely how they shop offline, according to Andrew Robertson, CEO at advertising agency BBDO.

Men tend to be very task-focused when they shop online, Robertson said. "They don't shop, they hunt," he said, adding that they tend to make purchases at night.

Women, however, tend to think of shopping as "a journey" and they are more likely to buy during their lunch breaks between noon and 1 p.m., he said.

The result: When it comes time to make a purchase, men shop online for an average of 10 minutes before they complete their purchase, while a woman may take about 14 minutes or so -- or about 40% longer.
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So why can't a woman shop more like a man? The answer is: she can. But that tends to occur when the pressure is on to make a speedy purchase. For example, on a day like Black Friday or Cyber Monday the gender gap narrows, according to Robertson.

He thinks retailers need to keep these distinctions in mind when they design their online and mobile commerce Web sites.

When it comes to mobile shopping, Robertson's research shows men are more likely than woman to buy gifts on their smartphones (17.6% and 10.8%, respectively).

That suggests mobile sites need to be designed for shoppers who want to make quick, focused searches, because that is a quality that men seek.

Sites that cater to women, on the other hand, want to make sure that they allow shoppers to meander around the site easily and are able to extend or tweak their shopping as they go. This style makes shopping more of an opportunity for discovery. They also seek out suggestions and opinions from their friends about their potential purchase.

Robertson said he thinks this is why daily deal sites such as Groupon ( GRPN), Living Social, and Rue La La have been so successful.

"They are opening up a journey," he said. The invitations to come see a deal on Marc Jacobs sunglasses for example, welcomes you to browse and see what else is there.