From Jim Butler's press release
What's in Spells & Magic? Well, here's a rough breakdown:
20 New Feats; 10 New Prestige Classes [Blood Mage, Dragon Mage (of which there are three types), Faerier, Reflecting Master, Jewel Mage, Soul Gem Guardian, Rune Mage, Shadetouched, Spellsinger, Totem Mage]; 124 New Spells (and they're not all just for wizards and sorcerers; a number of cool bard, paladin, druid, and ranger spells await other casters); Strange Brews (10 brews that show the effects of placing 4th-level and higher effects into potions, along with rules to make more brews); 40 New Magic Items, weapon qualities, armor qualities, and other cool tidbits.
I believe S&M is 96 pages and full color while S&S is over a hundred but black and white, includes rules for golem creation, rituals, chaos magic, research and libraries, a few spells, and bard, sorcerer, and cleric variants.
I don't have either, yet.