It made a big difference.
The more experiences a soul has in their life, the more anima their soul contains.
Night Elves are immortal (unless killed), and many have lived for hundreds of lifetimes.
According to a Quora answer, Sylvanas killed between 15–20,000 Night Elves. According to the Wiki most Night Elves live around several thousand years.
So lets be fair and assume she killed the lower end of that amount, 15,000 Night elves. And lets assume they all died at a pretty young age, around 1500.
15,000 * 1500 = 22,500,000.
That is how many years of life experience Sylvanas sent into the Maw. And that's when I'm lowballing the number. Using more accurate numbers (like averages instead of the lower ends) the amount increases exponentially.
- - - Updated - - -
Option a isn't needed, thanks to Sargeras. Either:
1. Sargeras killed entire planets worth of souls and the Jailer got them
2. The souls killed by Sargeras got obliterated (because of Fel) and the Jailer never got them, meaning Sylvanas' work on Azeroth is worth every soul
For option b, yes they are worth more actually. Specifically Night Elf souls.
How much Anima a soul has is determined by the amount of experiences in life a soul accumulates. The longer you live the more Anima you have.
And Night Elves can live for multiple thousands of years.