It is better to look up reflective verbs in a dictionary without reducing them to simpler forms.
собираться
1) (сосредоточиваться в одном месте) gather (together), assemble
2) (готовиться) prepare (for); (собирать вещи) pack up one's things
3) (+ ; намереваться) intend (+ to ) , be going (+ to ) , plan (+ to )
As you can see, the meaning 3) is completely missing in the non-reflective verb собирать.