Between-groups vs. within-subjects designs

What is the difference between a between-groups design (i.e. traditional ANOVA) and a within-subjects design (i.e. repeated measures ANOVA)?

50 XP

In a between-groups design, each subject is exposed to two or more treatments or conditions over time. In a within-subjects design, each subject is allocated to exactly one treatment or condition.
In a between-groups design, each subject is allocated to exactly one treatment or condition. In a within-subjects design, each subject is exposed to two or more treatments or conditions over time.