NTAG or MIFARE Ultralight: does the difference matter to you?
For most buyers, no. Both are Type 2 families read by every phone with NFC, so the compatibility question that worries people is already answered. The differences are in memory sizes and in features such as password protection and mirroring, which matter only if you need them.
What they have in common
Both are Type 2 tag families. Both are read by every phone with NFC hardware, on both platforms, without special software. Both hold NDEF content, both can be locked, and both cost cents.
For a deployment that writes a web address and expects members of the public to tap it, that shared ground covers everything that matters. The choice between them is genuinely not a decision.
Where they differ
Available memory sizes differ across the two families, so a specific requirement may be met by one family and not the other at the size you want.
Feature availability differs, particularly around password protection, read counters and mirroring. These vary by reference within each family rather than cleanly between families, which is why comparing family names is the wrong level of detail.
And configuration layouts differ, which matters only if you address configuration pages directly.
When the difference matters
When you need mirroring and only one available reference offers it. That is a real constraint and it is a reference level question rather than a family level one.
When a specific memory size is required and only one family stocks it at your supplier.
When an existing deployment used one family and consistency matters for the tooling around it.
Outside those, the two are interchangeable for practical purposes and choosing between them on brand preference is choosing on nothing.
The better question
Stop asking which family and start asking three things about the specific reference.
What is the NFC Forum tag type. What is the usable free space, not the total memory. And which features does it support, naming password protection and mirroring explicitly.
Those three answers determine whether a chip suits your deployment. The family name adds nothing to them, and a supplier who answers with a family name has not answered.
Frequently asked questions
Is one of them better supported by phones?
No. Both are Type 2 and both are read universally. The compatibility concern that drives this question does not apply to either.
Which is cheaper?
Prices track the memory size and the order quantity far more than the family. Comparing two references of the same capacity usually shows little difference.
Does MIFARE Ultralight have the same problems as MIFARE Classic?
No, and conflating them is a common and costly mistake. Ultralight follows a Forum tag type and reads everywhere, while Classic uses a proprietary layer with uneven device support.
Should I specify a family in a purchase order?
Specify the tag type, the minimum free space and the features you need. A family name without those is a weaker specification, not a stronger one.