The increasing of product market demands leads to contionous improvement of computerized numerical control (CNC) machine tools. This improvement requires real understanding of machines productivity, accuracy and operating parameters i.e. speed, flexibility and machine errors. The accuracy of machine tools can be increased by innovative designs, control, operating softwares and determination of machine errors. Such machine errors can be accurately identified through measurements. Machine tools include production and manufacturing machines i.e. turning, lathe, drilling and milling machines whatever computerized numerical control type or manuall type. Such machine types have different errors sources i.e. angular errors, horizontal and vertical straightness errors, paralleism errors and squarness errors are clear examples of these sources. In this paper, a comparative study for the determination of Machine Tools errors is investigated. Two main instruments of laser interferometer system and autocollimator system are used. The geometric errors are identified, measured and analyzed.