I lived in Hawaii for 6 months last year, and had opportunity to make many foreign friends there. Some knew well about Japan while others didn't, of course. One day, one of my European friends asked me "Do you eat sushi every day?" No! We don't eat sushi daily unless we are 寿司職人(Sushi-Shokunin: Sushi chef) !!
Keep talking about Japanese people and culture, we are not living in traditional styles. We don't wear 着物(Kimono) often, actually I do, but most of Japanese don't. We have few chance to be dressed in it... to attend some ceremony in childhood, and many girls wear it at the age of 20 to celebrate coming of age. Also, only one or two of my friends have experienced 茶道(Sa-dou :tea-ceremony) , and it's same as ikebana.
When explaining ikebana, we call it as "Japanese flower arrangement". It's correct because the word 生け花(or いけばな, ikebana) is made of 生ける(orいける, ike-ru ; to arrange) and 花(or はな hana; flowers). But ikebana and flower arrangement is technically different. Some of my Japanese friends don't know it, so I tell them briefly as below.
Flower arrangement is basically like these.
Make round or other kind of shape by adding flowers and leaves. Containers are full of flowers.
While ikebana looks like this.
We use least materials and make space between flowers to create the shape. The space between and around the materials consist the arrangement.
In other words, flower arrangement is made by + (plus, adding), and ikebana is -(minus, cutting). So these are technically not the same.
I don't want to confuse you, but the story above is about the very BASIC ikebana. When we finish basic lessons, we do it freely as below.
I call it "ikebana", but some might say it is "flower arrangement". Yes, both are correct... Even though I am ikebana teacher, it is difficult to clearly define...