I'm both an envious and a jealous person:
I'm envious of other girls who are more beautiful or artistically talented than I am; the feelings of envy become very strong if the girl is within the same age group as I am.
I become jealous if any of my sisters gets too close (either physically or emotionally) to my mom. I used to feel jealous of my oldest sister, because she lives in a foreign country and my mom would make a big deal about her coming to visit. However, that sister no longer "poses a threat", since my mom doesn't seem too excited over her anymore. I often feel jealous of my other sister because, well... she's extremely jealous of me; and we always subtly compete for our mom's undivided attention. I also felt somewhat jealous of my nephew when he was born, because my mom had to spend a lot of time teaching my sister how to care for him (he was my sister's first child). Now he's 3, and I don't feel threatened by him anymore.
I don't feel competitive with my dad or brother, however, because I realize that the relationships between husband/wife and mother/son pose no risk to my mother/daughter relationship. The only time I get angry with my brother is when he takes my spot on the couch beside my mom.
But, y'know, I've come to realize something that always quells my jealousy: my mom continually drops hints, in both dialog and mannerisms, that she secretly favors me above my siblings. My dad has noticed this also and has commented that, because I am more "helpless" than my siblings in the sense that I am autistic, my mother's instinct to nurture me is more powerful than her instinct to nurture my higher-functioning siblings who are not autistic.