- Ich komme gern, aber ich kenne die Adresse nicht.
- Ich komme gern, aber die Adresse kenne ich nicht.
(1) is the most common word order (subject - verb - object).
By putting Adresse in front of the verb, (2) puts more emphasis on the fact that the address is missing.
Compare the following sentence from Franz Kafka:
Einen Wagen hatte ich [...], aber das Pferd fehlte, das Pferd.
Here the fact that a car is available (as opposed to the horse) is stressed by putting einen Wagen (the object - more commonly placed after the verb) before the verb.
As already explained in another comment the main difference is in the emphasis of the word "Adresse". In general, whenever you have something that is not the subject in the first position of a sentence, it means that it is emphasised, similar to English.
Translating to English your sentences would be:
Ich komme gern, aber ich kenne die Adresse nicht. I gladly come, but I do not know the address.
- Ich komme gern, aber die Adresse kenne ich nicht. I gladly come, the address, though, I do not know.
I would like to point out that your examples both include
Ich komme gerne
which means "I like coming" which to me looks incorrect in both languages
I would personally advise
Ich möchte zu komme
Which uses möchte in the sense of "would like"
(want would work to, but the former is better in this case)
implying that you would like to come
I hope this helps you(I would have written this in a comment, but my reputation is less than 50.) If you do have a particular reason for using "Ich komme gerne" please tell me.