Article deals with comparison of cutting forces and surface roughness between materials produced by powder metallurgy -M390 and M398 Microclean® from producer, company Böhler. Main interest is the analysis and comparison of the cutting forces and surface roughness after the processing by cutting inserts with DNMG and WNMG geometry, radius 0.4 and 0.8 mm, after hard turning at the same process parameters for both materials and all four types of cutting inserts. The comparative studies were carried out for cutting forces and surface roughness with the aiming to observe the difference between "old generation" M390 and "new generation" M398 PM Steel for future processing in production. The corelation between the cutting forces and surface roughness was investigated. The measurement results indicate that the M398 is necessary to process with higher cutting forces which are linked with higher surface roughness than for M390. It is in relation with higher contain of additive elements in M398 and carbides formed by them even that both materials are in delivered condition soft annealed, containing Ferrite instead of Martensite [1], [2]. No less significant is influence of the type of cutting insert. The WNMG geometry showed better results for processing of both materials and is more suitable for their processing as well as radius 0.8 reached superior cutting parameters and surface roughness than 0.4. The result of this experiment is the selection of the appropriate geometry of the cutting insert, together with the determination of the correct parameters for machining the investigated materials supported by the results of the experiment. Suitable combination of cutting inserts and cutting parameters can reduce the time and energy requirements to process these high-quality steels. The results of this experiment helped to fulfil the knowledge about both materials in the row of experiments which are provided to increase material properties against abrasion and wear.