Fluke is considered to be the top and the leading multimeter brands in the market. Fluke 115 and 117 are its best RMS digital multimeters that often gets customers confused as to which one is better. However, their key features are more or less the same. The biggest difference between the two is that 117 has an automatic AC/DC selection feature, while 115 does not. The 117 is also relatively advance because of its low input impedance feature that prevents false readings. This feature is also not present in the 115 model. Fluke 117 is a more professional digital multimeter that has more advanced and technical features. 115 is a better option for beginners or common use.