Both versions are grammatical. Both versions have the same interpretations. :)
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The first version (which uses a "past tense" for modal remoteness) is more commonly used, though it is seldom formally taught in school as part of "classroom grammar".
Your second version uses the irrealis "were" to obtain that modal remoteness. This irrealis "were" is the last remnant of an inflectional mood system that has been almost entirely lost – what it was used for is nowadays done via tense (as done in your first version which uses the "past tense"). Some consider the version with irrealis "were" to sometimes be a bit more of a formal style than the first. Irrealis "were" is often emphasized in "classroom grammar"; but your speech or writing might sound affected if you use the irrealis "were" too much.