The two terms get used interchangeably, including by companies selling both. They are not the same, and the difference is occasionally expensive.
An electronic signature is a legal concept: any electronic indication that a person intended to sign. A digital signature is a cryptographic technique: a mathematical construction that binds a document to a key holder and reveals tampering.
One is about intent. The other is about proof. Most documents need only the first, but when you need the second, nothing else substitutes.
Electronic signatures
An electronic signature is broad enough to cover almost any deliberate electronic mark: typing your name at the bottom of an email, drawing a squiggle with a trackpad, clicking a button labelled "I agree", or pasting an image of your handwritten signature into a PDF.
Under the US ESIGN Act (2000) and the EU's eIDAS regulation, these are generally as legally valid as ink on paper for most transactions. A contract is not void because it was signed by drawing on a touchscreen.
What an electronic signature does not provide is proof. A drawn signature in a PDF is an image sitting on a page. It carries no cryptographic link to you and no evidence about the document's state when you signed it. If someone alters a clause after you sign, the signature image sits there looking exactly as valid as before, because it has no relationship to the content around it.
In practice, electronic signatures are usually backed by circumstantial evidence rather than mathematical proof: the platform's audit trail, the email address the signing link went to, IP addresses, timestamps. That evidence lives with the service provider, not in the document.
Digital signatures
A digital signature is a specific cryptographic operation. In simplified terms:
- The document is hashed, producing a fixed-length fingerprint of its exact bytes.
- That hash is encrypted with the signer's private key, which only they hold.
- The result is embedded in the PDF along with the signer's public certificate.
Anyone can now verify it. A viewer recomputes the hash of the document, decrypts the signature with the public key, and compares. If they match, two things are established: the document has not changed by even one byte since signing, and it was signed by whoever holds the private key corresponding to that certificate.
Change a single character and the hash no longer matches. The signature does not merely become suspect — it becomes cryptographically invalid, and the viewer says so.
This is why Acrobat shows a green tick or a warning banner on signed documents. It is performing that verification when the file opens.
The chain of trust rests on the certificate, which is issued by a Certificate Authority that verified the holder's identity. A self-signed certificate provides tamper-evidence but no identity assurance, because nobody vouched for who created it.
The legal tiers
eIDAS formalises three levels, and the vocabulary is worth knowing because vendors use it:
Simple Electronic Signature (SES). The broad category. A drawn or typed signature. Admissible, but its evidential weight depends on surrounding circumstances.
Advanced Electronic Signature (AES). Uniquely linked to the signer, capable of identifying them, created with means under their sole control, and linked to the data such that later changes are detectable. In practice this means a digital signature.
Qualified Electronic Signature (QES). An advanced signature created with a certified secure device using a qualified certificate. Under eIDAS, a QES carries the same legal effect as a handwritten signature across the EU, with the burden of proof reversed — the challenger must prove it invalid.
Other jurisdictions structure this differently. India's IT Act 2000 recognises digital signatures backed by Digital Signature Certificates from licensed Certifying Authorities, required for company filings, tax returns, and government tenders. The US takes a more technology-neutral approach, with ESIGN treating most electronic signatures as valid without mandating a specific method.
Which do you need?
Electronic is fine for: internal approvals, NDAs, employment offers, service agreements, rental contracts, consent forms, delivery confirmations. The overwhelming majority of everyday signing.
Digital is required or strongly advisable for: government and regulatory filings, tax submissions, tenders, court documents in many jurisdictions, anything where you must prove the document is unaltered years later, and anything crossing a border where local law demands a qualified signature.
The deciding question is not "how important is this document" but "will anyone need to prove, later and possibly in front of a court, that this exact text is what was signed?" If yes, you need cryptography. If the answer is really "we just need a record that both parties agreed", an electronic signature is sufficient and far less friction.
What our tool does, and does not do
Worth stating plainly: our Sign PDF tool produces electronic signatures. You draw or type a signature and place it on the page. That is legally valid for the broad category of documents above, and it is what most people signing a PDF actually need.
It does not produce digital signatures. Doing so requires a private key and a certificate issued by a Certificate Authority after verifying your identity — that is an identity-verification service, not a browser tool, and it cannot be done entirely client-side by design. If you need a QES for an EU filing or a DSC for an Indian government submission, you need a licensed provider, and any browser tool claiming to issue one should be treated with suspicion.
The distinction in one line
An electronic signature records that you agreed. A digital signature proves what you agreed to.
