Is there a difference between the nuccore and nucleotide entrez databases? In my simple tests they seem to return the same data. However [the biopython tutorial][1] makes use of both of them.

My testing from python:

```py
Entrez.read(Entrez.einfo(db='nuccore'))["DbInfo"]["Description"]
'Core Nucleotide db'

Entrez.read(Entrez.einfo(db='nuccore'))["DbInfo"]["Count"]
'202831776'

Entrez.read(Entrez.einfo(db='nucleotide'))["DbInfo"]["Description"]
'Core Nucleotide db'

Entrez.read(Entrez.einfo(db='nucleotide'))["DbInfo"]["Count"]
'202831776'
```

I also tried using efetch and didn't see any differences in the returned data.

 [1]: http://biopython.org/DIST/docs/tutorial/Tutorial.html
When trying to figure out the difference between the two databases, I also ran the same commands on the database descriptions, which indicates to me that they are the same database.

In the Biopython tutorial under Chapter 9, it mentions "The `Bio.Entrez` module makes use of the Entrez Programming Utilities (also known as EUtils)." According to NCBI's book "Entrez Programming Utilities Help", the nuccore database is just E-utility database name corresponding to [the Nucleotide Entrez database](http://www.ncbi.nlm.nih.gov/books/NBK25497/table/chapter2.T._entrez_unique_identifiers_ui/?report=objectonly).

Additionally, going to the Nucleotide database on NCBI, I notice "nuccore" in [the web address](http://www.ncbi.nlm.nih.gov/nuccore).

So I think they're the same database :)