Data tags and notes both let you record information that doesn't fit neatly into an existing field in Hortis. This might be details specific to your garden, or things that are hard to formalise into structured data.
Both are searchable, but they work differently. Data tags are reusable. Once created, they become part of a shared vocabulary that your whole team can apply consistently across records. Notes are free text, written fresh each time and specific to that one entry.
That's really the key to choosing between them. Use a data tag when the information helps you group or categorise a set of records, something you'll want to search or list later on. A taxon characteristic like "Autumn colour," or a collection designation like "Historic collection," are good examples. Many records can share the trait, so being able to pull up all of them at once is useful.
Use a note when the information is specific to a single record rather than a category. A description of a taxon, or an observation about the condition of one particular plant, usually belongs here. It matters for that record, but there's no real need to reuse or search it across others.
Notes are also a good home for information that repeats across many records but still doesn't fit a data tag or existing field, usually because each instance has a different value. A purchase order number for an accession is a good example. You'll want to record it for many accessions, but a data tag doesn't work well for something that's essentially unique data per record. In cases like this, we recommend recording the information consistently, using the same format every time, for example "PO number: 4560," so you can later search the accession notes for a specific purchase order.
A simple test: if you can picture wanting to search for every record that shares a characteristic, use a data tag. If the information only applies to one or a few records and isn't meant to support that kind of analysis, add a note instead.