difference on seda versus threads usage

[Robson Vargas Farias]

I'm trying to figure out the real world usage on both asynchronous
options... even trying to fit a way where I could mix ... but not sure
whether this makes sense...

so, the question is, what's the basic difference using one or another, like:

<from uri="direct:in"/>
<threads executorServiceRef="my20PoolSizeThreadPool">
  <to Uri="mock:out"/>
</threads>

versus

<route>
  <from
    uri="seda:in=20"/>
    <to Uri="mock:out"/>
</route>