One of the relatively recent trends in learner corpora research is building and exploiting learner translator corpora. Within corpus-based translation studies (CTS) translations are approached as a special variety of the target language. They are usually represented by texts produced by professional translators and are studied as manifestations of the current translational norm. Learner translations can be seen as a more specific variant of the said variety, which is likely to deviate from the accepted translational norm. As of now, typical linguistic features of learner translations as opposed to professional ones are only tentatively described. We hypothesize that these texts should demonstrate heavier translationese features due to the lack of professional translational skills, comparatively poor source language processing competence and target language production skills. The aim of this research is to compare learner and professional Russian translations of English mass-media texts with the reference Russian corpus of non-translations to reveal lexical differences between the three. We found that learner translations consistently showed more distance from non-translations than their professional counterparts, while both learner and professional translations undoubtedly had discursive features which made them linguistically different from naturally occurring language. These findings might help define (non)professionalism in translation and shed light on correlation between the linguistic features of a given text and translation quality, as well as contribute to pedagogical approaches to translator education.