People use "invoice," "bill," and "receipt" as if they're interchangeable — in casual conversation they mostly are. In your actual business records, they mean three different things, and mixing them up is a common source of confusion with clients and accountants alike.
Invoice: a request for payment, sent before you're paid
An invoice is what you send to ask for money — it lists what was provided, the amount owed, and when payment is due. It exists before payment happens. If you're sending it to get paid, it's an invoice.
Bill: mostly the same thing, from the other side
"Bill" isn't a distinct document type so much as a perspective shift — the same document you call an invoice is often called a "bill" by the person who has to pay it. Utility companies "bill" you; you don't typically "invoice" your electricity provider. In casual freelance use, people say "send me the bill" and "send me the invoice" to mean the same thing — but if you're being precise, invoice is the correct term for what you're issuing.
Receipt: proof that payment already happened
A receipt is issued after money changes hands — it confirms an amount was paid, on what date, by what method. This is the key distinction that actually matters: an invoice is a request, a receipt is a confirmation. They are never the same document at the same time, though a single document can serve both purposes at different points — an invoice stamped "PAID" with a payment date added effectively becomes a receipt.
Why the distinction actually matters
- For your bookkeeping: invoices track what you're owed (accounts receivable); receipts track what's actually been collected. Confusing the two makes it hard to know your real cash position.
- For your client: some clients' accounting departments specifically need a receipt — not an invoice — to close out an expense, especially for reimbursable costs. Sending an invoice when they asked for a receipt can genuinely stall their internal process.
- For disputes: if a payment question ever comes up, "I have the invoice showing what was owed and a receipt showing it was paid" is a much stronger position than one ambiguous document trying to do both jobs.
The practical takeaway
Send an invoice when you want to get paid. Once paid, mark it as such — ideally in a way you can hand the client proof of payment if they ask, whether that's a formally separate receipt or the same invoice clearly updated with a paid status and date. Keeping this distinction clean, even informally, saves confusion on both sides.