Three SBS Transit services cross at Woodlands into Johor Bahru — different starting points, one shared queue at the checkpoint.
If Causeway Link's CW buses are the scheduled coach option, SBS Transit's 160, 170 and 170X are the everyday-fare alternative — regular public buses that happen to cross an international border, all funnelling through Woodlands Checkpoint specifically. None of the three touches Tuas.
Worth flagging since it's an easy mix-up: 160 has nothing to do with Tuas, despite older listings occasionally implying otherwise. All three also terminate well past the checkpoint itself, at JB Sentral or Larkin — not at the checkpoint gate.
At Woodlands Checkpoint heading into JB, 160, 170, 170X and SMRT's 950 all share a single queue — you don't need to pick the "right" one in advance if any of the four gets you close enough to where you're going. If you need to switch between them after clearing immigration, tap out and back in within 45 minutes and no extra fare applies.
170X is the quickest way across if you're near Kranji, but it only reaches JB Sentral — if you're headed to Larkin specifically, only 170 gets you there directly. 160 makes sense mainly if you're already at Jurong Town Hall; otherwise Queen Street's more central starting point usually makes 170 or 170X the easier pick from town.