Lingo readings are taken from the interstitial fluid (ISF), a thin layer of fluid that surrounds the cells of the tissues below your skin, whereas a finger prick device uses blood as the basis for glucose readings.
Blood glucose readings tend to be about 5 to 10 minutes ahead of interstitial glucose readings. Because glucose levels are continuously changing, sometimes significantly, and there is a delay between values, you could see different values being reported by each device at the same time point.
References:
Basu A, et al. J Diabetes Sci Technol. 2015 Jan;9(1):63-8. Time Lag of Glucose From Intravascular to Interstitial Compartment in Type 1 Diabetes - PMC (nih.gov)