1. Tense: "Hiked" indicates the past tense. It means that the action of hiking happened in the past.
2. Voice: It also changes the voice from active to passive. While "hike" is an action verb (someone hikes), "hiked" can be used passively to indicate that something was hiked, like "The trail was hiked by many people."
So, "hiked" specifically refers to a completed action of hiking, while "hike" can be used in the present tense (I hike) or the future tense (I will hike).