The biggest difference is Early Bird is 2 years of service with one team(or traded contract) and cannot receive a contract longer than 4 years and cannot be shorter than 2 years. Full Bird is 3 years with one team(or traded contract) and can receive a 5 year max and a 1 year deal as well.
Cap holds in free agency work as such(since it's relevant to looking at bird and such)-
**Larry Bird [not coming off rookie scale contract] 150%-190% of his previous salary depending on the previous salary falling at(or above) or below the average nba salary.(190% below 150% at or above)
**Larry Bird [following the fourth season of his rookie scale contract] Same as above but the modifiers are 200% and 250% respectively.
**Larry Bird [following the 2nd or third season of his rookie scale contract] The maximum salary the team can offer him
**Any other Bird(non rookie) 130% of previous salary
**Any non bird(1 year) 120% of previous salary
-Also cap holds cannot exceed a players maximum salary nor can they be less than his minimum salary.
We have early bird on Powell, and we have full bird on zaza.
Source:
http://www.cbafaq.com/salarycap.htm