Based on my answer to First it says everyone had their own language; but then it says all spoke one before being split, we see that at the very least Radak (Bereishis 10:5 and here) and RDZ Hoffman understand them to mean the same thing. Many other Mefarshim to Bereishis 11:1 understand the same way (see Ralbag Biur Haparsha, Ibn Ezra I as examples, as they both say this clearly).
However, Ri Bechor Shor has a fascinating understanding of Safah Achas:
ויהי כל הארץ שפה אחת ודברים אחדים – שהיו כולם יודעים ע׳ לשון.
Meaning, that all of the nations understood all 70 languages, and as a result, Safah would mean they could all understand each other's speech, but not the same language. (Rabbeinu Chaim Paltiel also adopts this approach.) Also, see R. Hirsch who comments similarly:
וכיחס "לשון" ל"שפה" - בהוראה המוחשית - כן גם בהוראה המופשטת. השפה היתה אחת, אך הלשונות היו שונות, הוה אומר: הם דיברו שפה אחת בדיאלקטים שונים.
I would love to check various translations, but I do not have many available to me at this point. Hope the above helps.