Figured this would help more than an explanation:
The yellow wire on top is a carbon wrap core.
The black wire on the bottom is a stranded core wire.
(Dont go by the insulator jacket color, they each come in every color under the sun)
As a side note: the wire itself can be purchased by the foot, thus being able to re-use the caps in many cases. Quite often, on Porsche race wire sets we simply replace the wire and utilize the original boots. Why? The wire can be purchased for about $30 for a 4 banger, -vs- $160 for a whole new set!! just in case your doing this on a budget
"They that can give up essential liberty to obtain a little temporary safety deserve neither safety nor liberty" - Ben Franklin
2012-2013 miles - 68 (Not bad for Indiana!!)