Ariadna's highlanders lost the technology and kept the temper. The Caledonian Combat Force is built on colonists stranded far from the Human Sphere's comforts, fighting with what they have and closing the distance because that is where their advantage is, and it remains one of the game's most characterful armies.
A repack gathers existing sculpts into current packaging. That is genuinely useful for a sectorial with a long history, because it puts models back within reach without sending you hunting through the secondary market for boxes that left the catalogue years ago.
Metal and resin, unpainted and unassembled. Ariadna is a decent faction for a newer player because its troops are cheap, numerous and easy to understand, but a repack assumes you know which units your list is short of. If Infinity is new to you entirely, start with a two player set and let this fill the gaps afterwards.