The difference between Banksia and Bottlebrush are significant, I'm not trying to be smart about this but perchance do you mean "the difference between melaleuca and bottlebrush?" which a very similar.

Banksia belong to the PROTACEAE family while Bottlebrush (Callistimon) belong to the MYRTACAE family. Banksias have distinct seed cones while Bottlebrushes have individual seed capsules clustered along a branch.

No doubt about that Tony, they're like chalk and cheese I reckon. Even the melaleucas, though belonging to the same family as callistemons (bottlebrushes) are distinctively different. To the casual observer, go to your local bot. gardens and just compare the flowers and leaves, particularly now, in spring.

The reason I posted this question is that the flowers of some banksias and bottlebrushes look very similar to me.
Thankyou to all who replied.

Okay, here is a really simple test: simply grasp the flower with your hand, if the flower feels soft then its a bottlebrush, if it feels stiff its a banksia.

PS: Before grasping the flower check for bees!!

goodonya tonyw.,.,,even an old geezer like me can get ya drift "if the flower feels soft then its a bottlebrush, if it feels stiff its a banksia."
palming a bottlebrush is a very soft and pleasant experience.
at the moment there are many aussie birds getting stuck into the them in me yard.

If the birds get stuck into 'em too much, Aussie, they might become stiff!! then you wouldn't know if it was a bottle-brush or a banksia! Maybe we should just leave it to the birds.

G'day funnelweb,.,I really dig spiders.Spesherly when I'm tanked.Big fanged lady huntsmen are favourite that I let have the run of me joint that I can hand feed insects too.It's a heap of fun playing tug of war with them when they latch on to a juicy big cricket.
Unfortunately for one of my huntsmen girls who I had watched and fed from a spiderling, my daily Grey Shrike Thrush visitor called Shrikey, ignored the curl grub I was offering him, darted up me kitchen window, grabbed the poor spider, bashed it to death on the counter and ate it.
Broke me heart.
PS, Auzziebloke is the only handle I go by.
There's a zillion "aussies" in circulation and I aint one of them.
eeeeeeeerz cheeeeeeeerz to your earz funnelweb.

I can see why they do look similar - I just had a look at some photos and there are some banksia flowers with bottlebrush-like form! Using sense of touch is a great idea. I would also look at the foliage as well. Bottlebrushes seem to usually have thinner leaves, banksias more varied - but I could be wrong, still learning here.