The difference between し and たり

し

 * Meaning: "and," "also," "moreover," "besides"

 * Usage: Connects two or more verbs, adjectives, or nouns in a sequential or cumulative manner.

   * Example:

     * 私は、勉強をしたし、テレビも見ました。

       * (I studied and watched TV.)

     * 彼は親切ですし、頭もいいです。

       * (He is kind and intelligent.)

たり

 * Meaning: "sometimes... sometimes...," "now... now..."

 * Usage: Connects two or more verbs to express alternating or varied actions.

   * Example:

     * 今日は買い物に行ったり、図書館に行ったりしました。

       * (Today I went shopping sometimes and went to the library sometimes.)

     * 彼は歌ったり、踊ったりするのが好きです。

       * (He likes to sing sometimes and dance sometimes.)

Key Differences

 * し: Emphasizes the coexistence or addition of things.

 * たり: Emphasizes the alternation or variety of actions.

In Summary

 * Use し when you want to list things that happen together or are true simultaneously.

 * Use たり when you want to describe actions that happen in a changing or varied manner.