Apple acknowledged in December that it had intentionally slowed iPhones with degraded batteries through software updates to avoid sudden shutdown problems, but denied it had ever done anything to intentionally shorten the life of a product.
The Italian agency hasn't explained its decision to fine Samsung, but Apple has been up front about what it did and why.
Apple and Samsung were fined €10m and €5m apiece following investigations that determined they held "unfair commercial practices". According to the statement, Apple pushed users to update to an iOS version which was "made for iPhone 7".
The investigation was launched in January by the Italian body responsible for monitoring competition between companies, and they discovered that software updates from both companies actually had a detrimental effect on the performance of their devices. Unfortunately for Apple, French law allows for fines as high as 5% of annual turnover or even jail time.
"We are disappointed with the Italian Competition Authority (ICA) decision", said Samsung in an email statement. It said back then that the companies may have infringed four separate articles of the country's consumers' code.
The decision to fine Samsung is a bit of a puzzler, as the performance impact of its updates hasn't attracted almost the same level of criticism as Apple's.
It also found that the certain updates for operating systems "caused serious malfunctions and significantly reduced performance, thus accelerating phones" substitution'. The authority also argued that Apple should have issued instructions about replacing the battery in the iPhone.
It added the two firms had not provided clients adequate information about the impact of the new software "or any means of restoring the original functionality of the products". Apple has also faced questions from the USA senate over the issue, as well as more than 60 separate lawsuits, which have been ordered to be consolidated into a single suit in the Northern District of California.
Apple was fined for specifically slowing down the iPhone 6 without users' consent.
The companies will be required to publish an "amending declaration" on their Italian websites with a link to the AGCM's ruling.