Bucks & Aaron,
Not to be confrontational, but it is perfectly acceptable in today's market (at least here in Nashville) to have the choruses different lyrically. However, they still need to be similar enough to each other to be distiguished as choruses. The melody and rhyme scheme should be the same between the choruses and they also should be similarly themed and support the hook, title & premise of the song and drive the point of the song home as Aaron stated.
In fact, it is quite in vogue right now to change one key line (usually before the hook) in each chorus. Again, this is from a Nashville perspective.
Aaron is a good writer and generally, I still think that this is a good "rule" to follow (chorus shouldn't change). I think as a beginning writer, it might be good to go with that premise and work your crafting around that. After awhile, you can learn when/how/why to bend that rule. But what do I know?
I was told this by a pro writer/consultant who I take occasional consulting sessions with. Here are a couple examples of my stuff with this kind of thing going on (I'm not holding myself out as a great writer to learn from, but these are the only examples I can think of off the top of my head).
This one was worked with the songwriting pro and I am in the process of rewriting (so this will undoubtably change), but he quite liked it over all. This is an example of the choruses being quite different. Notice though, that the last two lines of each chorus is EXACTLY the same and contains the hook:
Sins Of My Father
©2003 John K Scott
Verse:
I came sneaking in at 2 AM
Trying not to wake him up
But there he was waiting up again
Half asleep with his half-drunk coffee cup
He asked if I'd been drinking again, I lied
He said, hand me those keys, for the next month you can't drive
Chorus:
He said, Son, there's a lot that you don't know
I guess it's time to tell you now
Then what happened took me by surprise
'Cause I'd never seen him cry like he did that night
The night his soul poured out like water
The sins of my father
Verse:
He said, "You were still a baby
And your Old Man loved his beer
Your Mamma loved your Daddy
He'd stay out late, she'd wait up in fear
I guess that Friday night she had enough
She went to get him, and she dropped you here with us
Chorus:
When they cut back the twisted steel
They found your daddy behind the wheel
With your mamma right there by his side
Man, I'd never seen him cry like he did that night
The night his soul poured out like water
The sins of my father
Bridge:
To that point in my life that was the biggest shock I'd had
I stood and stared at my uncle, who I'd only known as dad
And I wondered why he had to hit me with his hell
And would it really ever have mattered if he'd kept it to himself
Verse:
I got a call from my best friend Ray
That next Friday night
He said, Come on out there's a party
I'll pick you up, we'll be there by nine
I said, I need to stay in and work some things out
I'll catch you Monday, let you know what it's all about
Chorus:
Row fifteen, plot twenty-eight
That’s the one right next to Ray's
And I might have been laid there by his side
Had my Uncle never shared what he did that night
The night his soul poured out like water
The sins of my father
This next one is an example of one line changing in each chorus to highlight and help twist the hook. Again, I worked with the pro on this one and he actually suggested doing this. I just got done rewriting this one (might still tweak it some) and it is on hold and has a good chance of getting cut with an up and coming female artist on an independent label with major distribution. Notice on this one the second to the last line of each chorus is differnent and sets up the hook just a bit differently as it relates to the preceding chorus/bridge:
Daddy's Little Girl
©2003 John K Scott
Verse:
Dear Dad, I'm thinking back to the day you helped me pack
How you'd dry your eyes and try not to let me see
But your tears betrayed the scenes that played in your head
Scenes that starred a younger me
My tears held back what I had to say
So now I need to write what I should have said that day
Chorus:
I need to fly, test my wings
Try a little taste of everything
Out here in this great big world
I might climb mountains, I may cross seas
But I'll always hold a piece of you in me
I may have lost my curls
Still, deep inside I'm daddy's little girl
Verse:
Now I'm slinging plates at a Nashville Waffle House
Chasing dreams by day and tips by night
But I never dreamed it would ever be this hard
I'll give you that one, Dad you were right
There are days I bet we both wish I was home
But you prepared me for this flight for 18 years or so
Chorus:
I need to fly, test my wings
Try a little taste of everything
Out here in this great big world
I might climb mountains, I may cross seas
But I'll always hold a piece of you in me
My wings may be unfurled
Still, deep inside I'm daddy's little girl
Bridge:
I'm sure the world will look and see
A woman on her own
But with your love and wisdom inside of me
I'll never really be alone
Chorus:
I need to fly, test my wings
Try a little taste of everything
Out here in this great big world
I might climb mountains, I may cross seas
But I'll always hold a piece of you in me
Like an oyster holds its pearl
Deep inside I'm daddy's little girl
Yeah I'm daddy's little girl
Like I said, I'm no expert and I think you should take Aaron's advice. Especially as you are starting out. It's good advice. I am just showing you a little bending of the rules above and hopefully explained a bit WHY I did it.
You can actually hear "Sins of My Father" (guitar/vocal work track) on my site if you wish. I took "Daddy's Little Girl" down since it's in play right now.
Good luck & I hope this novel is useful!!!