STANDARD
Standard leagues have 'Head-to-Head: Points' as the scoring format. In a Standard league, your team plays against another team each week, per the league's schedule. The team that accumulates the most fantasy points wins the matchup for the week. The results of each week's matchup, and overall winning percentage, will determine the regular season winner in non-playoff leagues. In playoff leagues, the top teams have a playoff period after which a winner is determined.
PPR
Point Per Reception (PPR) leagues add a point per reception made, placing an emphasis on receiving positions (RB, WR, and TE).
NOTE: When selecting PPR, points are awarded to the player (RB/WR/TE) catching the pass. This an all-or-nothing setting ie PPR cannot be restricted to a single position (ex. just WRs).