Best Answer: Promo credits are free credits you earn within the site by browsing new products once everyday, playing spinfree, etc. (I've listed them below.)
Promo credit is like a different currency. You can only use them to buy stuff from the catalog. You can not transfer them, you can not give gifts with them. And when you purchase a product with promo credits, the content creator who made the product earns 1 dev token, instead of the credit profit of their share. 1 dev token worth 10 credits, which is a whole another story.
Real credits are what you buy from the site, from reseller or with prepaid cards. Free credits worth real money and are transferable. You can also send gifts with them. Real credits are the real currency within IMVU which actually
acts like a currency.
As far as I know, you shouldn't trust MetaRL.
The ways to get free credits:
"A. There are many ways to earn credits. Here are the ways:
1. You can invite friends, to earn 500 credits for every invite with a unique and vaild email address. When they have their first and fifth 3D chat you earn another 500 credits. If they buy credits from IMVU you will earn between 1,000 and 10,000 credits every time they buy a credits pack.
2. Play the slots machine: http://www.imvu.com/catalog/web_spinfree. Every 24 hours you have the chance of winning 0-500 credits.
3. Check the new products every day http://www.imvu.com/catalog/products_new. Every 24 hours you will recieve 1-50 credits.
4. Becoming a developer and making quality products for other IMVUers to buy "