Microsoft, struggling to break into the tablet market, backed off plans to introduce a smaller version of its Surface tablet based on Qualcomm processors, people with knowledge of the decision said. Microsoft Chief Executive Officer Satya Nadella and Executive Vice President Stephen Elop decided that the product in development wasn’t different enough from rivals and probably wouldn’t be a hit, said one of the people, who asked not to be identified because the plans weren’t public. Engineers had been working on the device and had planned to unveil it as early as today at an event in New York, two of the people said. Instead, the company removed any references to Surface devices based on Qualcomm’s processors from the event and unveiled Surface Pro 3, an upgraded version of its pricier Windows-based tablet, which uses chips from Intel Corp.