Not necessarily, althought it may be a confusing of terms by our friends in the media. It seems that the Ranger element was conducting the raid, or had otherwise hit contact. The SEAL element appeared to have been either the IRF/QRF backup, or possibly the main element of the raid that was moving into support the Ranger cordon that landed first and hit contact. 'Rescue' is probably journalist shorthand for hairs we might have split a lot finer in the military.
Would 20 Seal Team members suit up to provide reinforcement for a pinned down Ranger team? I’m more given to believing that Rangers would mount up to relieve Rangers. They are rock solid about “leave no man behind.”
It seems they were all part of the same operation, which is not uncommon. Even as the 'rescue' appears more of a reinforcements plan with teams already in place kicking in to support the element in contact.
I have a pretty clear idea of what these next three answers are, but for the purpose of loose lips, I'm going to go with the abridged versions.
The questions would then remain how they planted intel with our SpecOps,
Trial and error. Feed us enough bait, see what we sniff and ignore, and what we eat, and sooner or later, you've got us.
how they knew the route the Seals would take,
Observation of our TTPs, based off of our actions in similar terrain. They likely picked a 'meeting spot' ambush site in terrain that only had one really good infil route.
and why the mission might have required a single airframe inserting a fairly large force.
Good old METT-TC there. Why the commanders went with that airframe over others is dependent on factors we don't know. It's certainly not unusual to fly Chinooks in Afghanistan.
see #51 above if you weren’t pinged