there no difference in the actual technique of arnis or eskrima, the difference is in who is teaching the style and what techniques does he select.
most of the new "combat oriented" stuff i seen lately is the same thing everyone else does,
drills
"live, combat" drills
sensitivity drills
pre-hispanic "authentic" style and techniques
"killing" techniques/blade only styles
"held-back", secret, or family arts
my opinion is the person who has the lineage people can authenticate will probably be a better teacher because he is more honest. but if you are looking for a true fighting style, the person teaching must have a few things (or at least what i look for):
-he is humble enough to say he trained with these different teachers, and this is what good stuff he got from them. beware of the man who abandon his old, useless style because the "FMA" is so deadly. thats garbage. every teacher you went to has good information, and i question the one who said "i took TKD, and they suck. but THIS, this stuff is for real..."
-he has people who knew him "when". many of the FMA "masters" i see been in it less than
7 or 8 years, maybe less. if look into the background of these guys, they are kung fu, kenpo, or whatever, and you can see it in there movement. there's nothing wrong with that, but are they honest?
-the fighting style. many good fighters will create his own technique. how did this person decide what techniques are better? in his gym with his students? or in the competition against the top fighters in his area? or did he go to the philippines to a poor old eskrimador and buy him gifts, in return for certification? does his techniques have what everyone else is doing? there are many people who have "improve" their jkd/fma whatever, but they are doing the same stuff all over again.
-finally, how did he convince you that his technique is good? did he tell you or describe it? or did he spar with you to prove it to you. most people will say "give me a hit here" but they dont want a full power hit. some will say "hit me" you pick the place you pick the speed and power, then they will show it.you tell me whose technique is better.
have you heard the saying that styles are a dime a dozen, and fighters are a dime a dozen, but a fighter who can teach a good style if you can find him is worth a million dollars-whatever you value your life for. don't be easily convince that arnis or eskrima or "kali" is better or different because it is who is teaching it and what did he experience. that is the only difference.