Russian and Romanian are very different, they belong to 2 different language groups, the former being a slavic language, the latter a romance language with a strong latin imprint (it's the only romance language that maintains the latin declension). As any other language, also Romanian was subject to linguistic influences through the centuries (German, French, Slavic, Turkish, Greek influences).
However, even if a person speaks and understand s Romanian pretty well, you can't say that he understands Russian as well or that listening to it he can get a sense of it. It could be probable for someone living in Moldova to understand both languages as in Moldova a lot of people speak Romanian and Russian or at least understand them, but I don't know how a person who has never been in Romania or Moldova could understand Romanian if she/he has never studied it (unless this person has a natural talent for foreign languages).