送料 and 料金: shipping costs and the direction of delivery
Separate shipping included in the item price from return shipping, checking conditions tied to direction and destination.
The cost of sending goods
送料, read そうりょう, means the cost of sending goods. 商品の代金とは別に送料がかかります。 says that shipping costs apply in addition to the item price.
送料込みの価格です。 indicates a price including shipping. 込み includes the named item, 送料, rather than necessarily every other additional charge.
The broader word for a charge
料金, read りょうきん, means a charge for a service or similar use. 配送の料金を発送前に確認しました。 says that the shipping charge was checked before dispatch.
送料は配送先によって変わります。 says that shipping costs in this notice vary by destination. Do not generalize it to every delivery service.
Outward shipping and shipping back
発送時の送料は無料ですが、返送時の送料は別です。 says that outward shipping is free, but return shipping is separate. Do not apply the free condition to both directions.
返送の送料は誰が払いますか。 asks who pays for return shipping. The word 送料 alone does not identify the seller or buyer as the payer.
Can return shipping be assumed to be free in 発送時の送料は無料ですが、返送時の送料は別です。?
Show the answer and why
No. The notice makes only outward shipping free and identifies return shipping separately, so its charge must be checked.