Those are differences in emphasis (DIgest vs diGEST). Tonal differences in Mandarin are more subtle. The same syllable is emphasized, but the "shaping" of the pronunciation is changed.

Also note that OP stated that he or she couldn't distinguish between Mandarin tones, not tonal differences in general. This is not difficult to believe, as your ear becomes trained to recognize differences in your native language and ignore slight differences in pronunciation that don't affect the meaning.

No, neither is necessarily any more or less subtle than the other. It all depends on the speaker, their dialect and accent, and the situation.