Quote, estimate, and invoice sound similar, but sending the wrong one can cost you money or set the wrong expectation. Here's the plain-English difference.
An estimate is your honest approximation of what a job will cost before you know every detail. It's not binding. Use it early in a conversation when the client just wants a ballpark — and always label it clearly as an estimate so nobody treats it as a fixed price.
A quote is a commitment: "I'll do this work for this price." Once the client accepts, that's the number. Quotes usually include an expiry ("valid for 30 days") so your pricing isn't held against you months later. Send a quote when you know the scope and you're ready to win the job.
An invoice comes after the work is done (or at an agreed milestone). It states exactly what's owed, the due date, and how to pay. This is the document that actually gets you paid.
ListWisp creates all four from the same short description of the job, so you can move from estimate to invoice without re-typing anything.