Side By Side Comparison of Lenovo A390 and Karbonn K21+. Compare Processor, display, RAM, Storage and other features here. You can quickly compare Lenovo A390 and Karbonn K21+ smartphones just by looking at their ratings and results showing "winner" and "runner up." There is also a short analysis comparing different features of Lenovo A390 and . You can also look at each hardware feature individually to perform your analysis while comparing mobile phones.