What are the difference between beliefern and liefern? I know that both mean to deliver but are they interchangeable?
Dameslaars Ankle Gev 36 Zwart 00 9143 Boots Zwart Women’s Chuva Noir Ct1wqxxgP
"liefern" requires info on what is being delivered, optionally to whom it gets delivered to.
"beliefern" is the other way round. You must define who gets it, but it's optional to state what gets delivered.
Note Hans Peter's examples and add the example
Ankle 00 Chuva 36 9143 Women’s Noir Boots Gev Zwart Dameslaars Zwart Wir liefern Tomaten.
for clarity of the usage.
beliefern is the transitive version of liefern. The former automatically asks for an (accusative) object. It's like the difference between antworten und beantworten:
antworten auf die Frage = die Frage beantworten