Dale Sohn, former chief executive officer of Samsung's American unit, has testified for the company in a patent lawsuit brought by iPhone maker Apple.

Apple is seeking $2bn (£1.2bn, €1.5bn) from Samsung for alleged copying of its designs and features in the South Korean company's new smartphone models.

In a previous trial in 2012, Apple highlighted the absence of witnesses for Samsung to deny claims of patent infringement.

Sohn's testimony was intended to differentiate Samsung's business model from that of Apple and thereby refute patent infringement claims by the iPhone maker, according to Bloomberg.

He currently serves in South Korea as an executive adviser to J K Shin, one of Samsung's chief executive officers.

Samsung is presently the smartphone market leader, accounting for one in three of all devices sold last year. In the smartphone market valued at $338.2bn in 2013, Samsung holds a 31% share, compared to Apple's 15%, according to data compiled by Bloomberg.

While Samsung continued to retain its global smartphone presence, Apple's market share has declined due to stiff competition from low-cost rivals such as LG and Lenovo.

During the trial in federal court in San Jose, California, Sohn noted that Samsung's US sales were sluggish when he joined the unit in 2006. He explained the company's turnaround in 2007, when Apple launched the iPhone, to become dominant in the US market. By the third quarter of 2008, Samsung became the No 1 market shareholder in mobile phones.

Sohn added that Samsung's marketing strategy was different from Apple, whose iPhone occupies a "niche market" because "not really many of the customer base could afford" it.

In order to defend claims that several Android operating system features in Galaxy devices infringe on Apple's patents, Samsung called engineers from Google, the maker of Android.

In the latest lawsuit, the iPhone maker accused Samsung of infringing on five patents on newer devices, including the fast-selling Galaxy smartphones and tablets. Apple claims that Samsung copied its tap-from-search feature that allows someone to call a phone number found online as well as the "slide to unlock" feature.

Samsung, in its counter claim, argues that Apple infringed on two of its patents on its iPhones and iPads. Apple has stolen a wireless technology system for speeding up sending and receiving data, Samsung alleges.

About two years ago, a federal jury found Samsung was infringing on Apple's patents and asked the South Korean electronics major to pay about $900m to Apple. Samsung is appealing the decision.