Both are ways of stopping someone trading under your brand. The difference is where the right comes from.
Infringement is a statutory remedy under Section 29 of the Trade Marks Act, 1999, and it is available only to the proprietor of a registered trademark. Passing off is a common law remedy that protects the goodwill built by actual use, and it does not require registration at all.
Section 27 draws the line explicitly: no action for infringement lies in respect of an unregistered trademark, but nothing in the Act affects the right of action against any person for passing off.
What you have to prove
This is the practical difference, and it is a large one.
For infringement, you prove your registration and that the defendant used a mark identical or deceptively similar to it, in the course of trade, in relation to goods or services covered by the registration. Your registration is itself evidence of your right. Where the marks and the goods are identical, confusion is presumed rather than proved.
For passing off, you prove three things, and all three are yours to establish. Goodwill or reputation attaching to your mark among the relevant public. Misrepresentation by the defendant leading or likely to lead the public to believe their goods are yours. And damage, actual or likely, flowing from that misrepresentation.
Establishing goodwill from scratch generally means years of evidence: sales figures, advertising spend, market presence, sometimes survey evidence. That is the burden registration removes.
Why registration is worth having
Put the two side by side and the case for registering becomes concrete rather than abstract.
An unregistered owner with real reputation is not without a remedy, and Indian courts have protected prior users robustly. But that owner carries the cost and risk of proving reputation every time, and a business that is young, regional or in a quiet sector may struggle to prove enough.
Registration also fixes the scope of the right in advance — the mark, the classes, the goods — where passing off is argued case by case on the facts of each dispute.
Deceptive similarity: the test courts apply
Both actions turn on whether the public would be confused, and the Indian approach is consistent.
The comparison is made through the eyes of a consumer of average intelligence and imperfect recollection, who does not see the two marks side by side but remembers one and later encounters the other. Marks are compared as a whole rather than dissected into elements.
Phonetic similarity carries considerable weight, which is why two marks spelled quite differently can still conflict. The nature of the goods, the class of purchaser and the trade channels all feed in, and a greater degree of care is expected from buyers of expensive or specialised products than from buyers of everyday items.
Where the goods are medicinal, courts apply a stricter standard still, on the reasoning that confusion there carries consequences beyond commercial loss.
Cadila Health Care v Cadila Pharmaceuticals is the leading authority on the factors to be weighed.
You can plead both
A registered proprietor who has also been using the mark is not confined to one route. It is standard to plead infringement and passing off together in the same suit.
That matters more than it sounds. Infringement is limited to the goods and services actually registered, so where a defendant is operating just outside your specification, the passing off claim can reach conduct the registration does not. Conversely, if the registration is later challenged, the passing off claim may survive independently.
Before you send anything
Two cautions are worth stating plainly.
Check what you actually own. A registration covers the mark as registered, for the classes registered. If the defendant is in a class you never applied for, your infringement claim may be weaker than you assume — which is the practical argument for filing in every class that carries real risk.
And be careful with threats. Section 142 of the Act gives a person who receives groundless threats of infringement proceedings the right to sue for a declaration and an injunction, and to recover damages. A strongly worded letter sent without a sound basis can turn you into the defendant.