What is the difference between the races elf and high elf?

Summary gleaned from Learning LOTRO, Lesson Ten, Racial Traits:

Elf:

• Silvan Shadows: Min. level 13; +Stealth.
• Friend of Man: Min. level 13; Fate boost.
• Tactics and Conviction Bonus: Min. level 19; Fellowship maneuvers.
• Elf Bow-damage Bonus: level 25; Bow damage.
• Return to Rivendell: Min. level 29; travel to Rivendell
• Elf One-handed Sword-damage Bonus: Min. level 30; Weapon damage.
• Virtuous Elf: Min. level 35; Purchaseable virtues.
• Power of the Eldar: Min. level 35; Fellowship power.
• Eldar's Grace: Min. level 35; Parry boost.

High Elf

• Grace of the Firstborn: Min. level 13; Speed boost.
• Wrath of the Firstborn: Min.level 19; Fellowship damage.
• Grace of Valinor: Min. level 25; Out-of-Combat revive/rez ally.
• Those Who Remain: Min. level 29; Will boost.
• Travel to Caras Galadhon: Min level 32; Travel to Caras Galadhon
• Enmity of Darkness. Min. level 35; Light damage boost
• Glory of the First Age: Min. level 38; Paralyze enemies.
• Blade Dancer: Min. at level 42; Sword skills.
• Virtuous High Elf: Min. level 60; Virtue boosts.

The High Elf starter quests are entirely new and feature starting at the Battle of Dagorlad and featuring Sauron's defeat by Isildur. See also this preview.

High Elves are able to roll every class except for Beornings and Burglars. High Elves look slightly different (particularly their hair). Whereas an elf can play as a Champion, Guardian, Hunter, Lore-master, Minstrel, Rune-keeper, or Warden, a High Elf can also play as a Captain.

High Elves have cool animation changes including a /dance3 emote that is somewhat like a ballet dance move. When falling, they do it very gracefully with a rolling animation.

Elf and High Elf have the same base stat adjustments:

• -20 Max Morale
• -60 Non-combat Morale Regen
• +15 Agility
• Fate -7
• +1% resistance to disease
• +1% resistance to poison

This YouTube video may be of interest: High Elves vs. Elves in LOTRO - What's the Difference?.