Registration puts your claim on title, publicly and dated. Notice does something structurally different, and it only exists because title registration isn't always available.
Short answer
Registering a lien means filing a document against the property’s title at a land or property registry, which converts an unpaid invoice into a secured, dated, public claim against the building itself. Giving notice is a different mechanic entirely, used precisely where registering against title isn’t available — on Crown land in Ontario, for example — and it redirects the security to money the payer holds instead of to the property.
BC’s Builders Lien Act is the clearest public example of what registration actually involves: a claim “must not be filed if the amount… is less than $200”, filed no later than 45 days after of a completion certificate or the improvement being finished or abandoned, and once filed it “takes effect from the time work began or the time the first material was supplied” — meaning it can outrank a mortgage advanced afterward. Alberta’s version runs through a different form entirely: a statement of lien in the prescribed form, filed with the Land Titles Registrar under s.34(1). Quebec runs the same underlying idea under a different name again — workers have up to 30 days after the work is finished to publish a legal hypothec on the property, giving construction workers a security interest without ever calling it a “lien.” Three provinces, three procedures, and none of the windows or forms transfer between them.
Ontario’s Crown-land carve-out is the working example: you do not register against title on Crown land — you give written notice, and the lien attaches to the holdback instead, so “notice” isn’t a simplified registration, it’s an entirely different target. See what happens if your project is Crown-owned for the practical playbook of when and how that notice actually gets used.
A registered lien is enforceable against anyone who checks title later — a buyer, a new lender, anyone doing due diligence on the property will see it. A notice never touches title at all, so its only value is whatever money is actually sitting in the fund it attaches to. That has a real practical consequence: due diligence on a Crown or public project has to substitute for the title search you can’t do — confirming the holdback is genuinely being retained, since there is no registry entry standing in for that confirmation. See how a statutory holdback works for what that retention obligation actually requires of the payer.
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