SAN JOSE, CALIFORNIA—The Apple v. Samsung trial started getting into technical details today, with afternoon testimony from Peter Bressler. Bressler is an industrial designer who is Apple's first expert witness and, unsurprisingly, he testified that Apple's trade dress and four design patents are infringed by Samsung smartphones and the Galaxy Tab 10.1.

But during a lengthy cross-examination, Samsung lawyer Charles Verhoeven focused on small differences between Apple's design patents and the accused Samsung phones.

"It is wider, yes," said Bressler, when asked about the side margin of the Samsung Infuse 4G (and yes, the phone's margins are wider than the margins described in Apple's D677 patent). "Again, this is a level of detail that the ordinary observer wouldn't see."

"Would you agree that they are they substantially different?" asked Verhoeven. "If the width is measured and it turns out to be a factor of 15 times wider, you think that's just a minor detail?"

Bressler hedged. "I think that's a factor of the overall design," he said. "You're asking me to compare peanut butter to turkey."

Verhoeven brought out more differences through his questioning: the Infuse has four buttons at the bottom rather than the iPhone's iconic single button; it has no bezel, as the iPhone has.

It wasn't until the end of the day that Verhoeven made sure the jury knew that Bressler's testimony is paid for by Apple—to the tune of $400 per hour.

"How much has Apple paid you so far?" asked Verhoeven.

"In this case, about $75,000," said Bressler.

Lawyers for the two electronics giants also feuded bitterly over what exhibits and demonstrative slides could be shown to the jury. US District Judge Lucy Koh, who is overseeing the case, clearly grew frustrated with lawyers on both sides. She has begun docking time from each side for the endless arguments over visual displays.

Testimony will continue Tuesday and Friday this week, and throughout the following week. Apple is slated to bring several different expert witnesses to the stand. Those experts include Russell Winer, a professor of marketing at NYU; and Ravin Balakrishnan, a computer scientist at the University of Toronto.

One notable non-expert who will soon be called to the stand: Susan Kare. She's a former Apple designer who created some of the earliest Macintosh graphics and icons.