Let put all of this to rest about the crazy style of DBZ releases we've had ever since it hit the states many years ago.
The Saiyan & Namek arcs that originally aired in the US were dubbed by Ocean, and was owned by Saban. This is where a lot of people first got into DBZ, and probably anime itself in the US. These episodes were heavily edited, had redone (and corny) scripts, scenes cut, music redone, etc. Overall, it was a mess, and it's really hard to watch.
After the Namek arc, Ocean continued dubbing DBZ elsewhere (you can find clips of it on YT), but in the US, Funimation grabbed the rights. Funimation retailed all of the name changes, some of the edits, and more or less got new actors to try and match the voices of the previous ones. From what I know, I don't think any VA from the original DBZ dub is in the more recent Funimation dub. Anyway, Funimation finished the series and then they finally got the rights for what they didn't do a few years ago.
Enter Dragonball Z Uncut. This originally aired on CN a few years ago completely unedited, and it was pretty damn awesome. Funimation redubbed and completely redid all of what Ocean previously did. I myself enjoyed it, but it still followed the style that Funimation picked up on before. Oddly enough, all they did at the time was just the Saiyan arc, so when the series hit the Namek arc on TV, it switched back to the old Ocean dub, which totally sucked.
Dragonball Z Uncut was released on individual DVDS for the first couple of volumes until Funimation screwed over their fans yet again, and finally decided to re-release them again in Season box sets. The orange box sets that are everywhere now for dirt cheap are digitally remasted by Funimation, claim to be in "HD", were cropped in wide screen, and Funimation swore that it was the shit.
Enter the Dragon boxes. This was Toei's

you to Funimation, since Toei properly remastered the series themselves. Funimation figured they would cash in on these sets as well and released these too. Screwing DBZ fans not once, but
twice.
Lastly, we got Dragon Ball Z Kai. This is done by Toei, and not Funimation. They upscaled the series to HD, got new music, redid the voice acting, edited down the episodes (rather nicely I heard), and removed all of the filler. These are currently released by Funimation with a new dub that claims to be close to the script, and they also redid their voice acting as well with a few new actors too. This is probably why Gohan and Frieza's voices no longer suck. Or at least this is what I hear (haven't watched it yet).
And that's it! No other explanations are needed, unless someone want's to correct on something, then that's fine.