Sorry. I've been lazy. Not much is different between versions.
Episode 8 in the new series contains the same amount of content from episode 13 in the old one. That's mainly because the old series began to pick up their pace, though. The last three pages of 14, chapters 15, 16, and ten pages of 17 are all covered.
First thing: This rock climber.
Same thing pretty much happens in both versions--the scenes are mostly just directed differently. Fun fact--the climber in the 1999 series is voiced by Yoshihiro Togashi: the creator of the series.
Lippo is introduced.
Minor differences: Lippo now has purple hair and isn't wearing sunglasses like the manga. A major difference is that Lippo isn't accompanied by two professional Hunters in the 1999 series--two convicts serve as his lackeys. The new series puts the Hunters back in.
In the 1999 series, Gon and Killua find the secret door in Trick Tower but Leorio and Kurapika are the ones who test and deduce how they work. In the manga and anime, Gon and Killua are the ones who observe how the doors work.
I like how the new series showed Gon playing with Killua's skateboard and Kil using Gon's fishing rod.
The interior lighting is different. The aesthetic is different.
Since there's a narrator (and wordboxes) in this series, information is conveyed in a less clunky manner. In the 1999 series, Lippo's prisoners have to talk about it so the viewer knows (because there's no narrator).
The characterization is different again. Tonpa says that his cowardice is the only reason why he became a rookie killer. After he states his betrayal, everyone in their party gets really mad (as opposed to here--it's only Leorio). Killua makes a move to kill Tonpa, but Gon says something obvious and stupid and Killua stops.
This guy comes out.
Gon wants to take him on!
Anyways, very similar episodes. Until next week.