A major difference between the two is that Google chose to offer a service similar to Spotify and Rdio. Thus, terms for the service type had largely been established. Apple on the other hand is looking to create a hybrid web and radio service more similar to Pandora but with some on-demand features.
"Of course [Apple's] negotiations were going to take longer," said one source.
Additionally, Google was willing to pay advances to some of the major copyright owners; however, Apple traditionally is unwilling to do that and at least initially didn't offer any advances. The company has agreed to pay content owners a share of the ad revenue, a per-play fee, and a minimum guarantee.
The report notes that Spotify-like subscription services are more lucrative for labels than radio services such as Pandora; stating, that if iRadio was a clone of Pandora it would never get licensed.
While Apple has differentiated itself from Pandora, Sony/ATV, the largest music publisher, has reportedly rejected Apple's terms and The Verge has learned that BMG Rights Management is also holding out. That being said, some of the industry's largest players are apparently excited about the service and would like to see it launch as soon as possible.