Hello, I hope someone can put me out of my misery because I'm confuzzled.

A couple of weeks ago I decided that my 'treat of the month' would be the sheet music of Handel's recorder sonatas (you don't need to look at it, I'm just linking things in for the curious among you).
I then found on eBay someone selling a very cheap CD of the same Handel's recorder sonatas (well, the six in the book are six of the eight on the CD). I thought this was fab as I could listen to a version of what I had bought myself to play

I finally listened to it yesterday, and two of the sonatas - the F and Bb - sounded awfully familiar. When I got home I hunted out the CD I have been listening to a lot lately of Baroque Recorder Concertos. Turns out, the two Handel pieces on there are a Concerto in F and a Concerto in Bb.

Now, I mentioned this to my husband who said maybe they just sounded a bit similar, but I'm convinced they are the same. I've not had the chance to sit down and play one CD followed by the other (while following along with my sheet music).

But my question, in complete ignorance, is could they be the same thing? Just they've called it a sonata when it's a recorder with cello + harpsichord on CD and when it's a recorder + bc sheet music; but then they've called it a concerto when they've stuck it in with a string orchestra + harpsichord on the other CD? A quick search on the net doesn't reveal any recorder concerti by Handel, just sonatas...which I guess answers my question!
I've looked on Wikipedia and even braved the online version of the Grove encyclopedia of music (which I get access to via the OU) but I'm still confused as to what the difference between sonata and concerto is (other than the latter has more orchestra behind the soloist!)

I'm guessing here, but I think that sonatas and concertos are often very similar in form and style and whether you call it a sonata or a concerto is down to the composer or arranger's preference. In general I would agree that a concerto is usually played with an orchestra, whereas a sonata would be played as a solo or with one or two other instruments.

Handel should be held up as a hero in this green age.......he did a lot of recycling!

Absotively! There's a bit on my newer CD where the rhythm/intervals make you think it's about to go in to Water Music but then it doesn't. Those opening three notes have certainly earned their 'green points'!

They definitely can be similar. Also I think Handel was historically just coming in at the end of a period when titles like sonata and concerto didn't necessarily have the same definite formal implications and fixed definitions that they later acquired, but were just beginning to be associated with particular forms, so it can be a bit confused (not to mention confusing )

It was common in those days for composers to make a different arrangement of their own or somebody else's music, so that could easily be the case here.

Mystery solved (yay for a morning off where I can listen to things with music in front of me).

Bb major sonata is the same on both CDs, and matches the sheet music. These are all recoder works.

F major sonata on the sonatas CD matches the sheet music, and is a recorder work.
The F major concerto on the concerto CD is completely different. I plead confusion over the fact that the sonatas were next to each other on the CD and being as I was driving I wasn't exactly sure which one I was looking in to.

My lovely book of sheet music has at the back a list of 'concordances' - which tells me that the 2nd movement of the recorder G minor sonata is equal to the 2nd movement of the E minor flute sonata, and so on.
Confusingly, this one also tells me that the F major sonata is used completely in the F major organ concerto (but perhaps it's a different F major organ concerto to the one for recorder on my concerto CD).

So, yes, you were all right, Handel did a lot of recycling and decided what to call it depending on the number of backing musicians