I have found that there is a distinct difference between solitude and loneliness.

The following are definitions of the word ‘solitude’ according to the dictionary:

1. the state of being or living alone; seclusion
Ex. to enjoy one’s solitude
2. remoteness from habitations, as of a place; absence of human activity
Ex. the solitude of the mountains
3. a lonely, unfrequented place
Ex. a solitude in the mountains

The following are definitions of the word ‘lonely’ according to the dictionary:

1. affected with, characterized by, or causing a depressing feeling of being alone; lonesome
2. destitute of sympathetic or friendly companionship, intercourse, support, etc.
Ex. a lonely exile
3. lone; solitary; without company; companionless
4. remote from places of human habitation; desolate; unfrequented; bleak
Ex. a lonely road
5. standing apart; isolated
Ex. a lonely tower

As one can see, solitude and loneliness are far from the same thing. Solitude implies that one enjoys isolation and desires isolation, while loneliness implies that one enjoys and desires the company of others.

Consider the following pairs of sentences:
I ate my dinner in solitude.
I ate my dinner alone.

I did my homework in solitude.
I did my homework alone.

I rode the bus in solitude.
I rode the bus alone.

I went to the mall in solitude.
I went to the mall alone.

I myself did each of these things at some point over the last week. If I were to describe my week to you using the first sentence in each pair, you would think that I had a very pleasant week and that I was taking advantage of opportunities to have some peace and quiet. However if I described my week to you using the second sentence in each pair, you would think that I had a very depressing week and that I did not enjoy the absence of companions.

Now the difference between solitude and loneliness is quite clear. What is unclear is if I spent my week in solitude or loneliness. I won’t say much on this matter, but I will say that my week was spent in both solitude and loneliness. Some days just happened to be more lonely than others.