As far as I know, "Merry Christmas" is more common in England and "Happy Holidays" in the States. For example - Merry Christmas, grandma! Merry Christmas, my child!
A) Merry Christmas
If you want to wish someone merry Christmas you can do so the following way :
A: Merry Christmas to you and your family!
B) Merry Christmas to you too !
I hope this helps :-)
A) Merry Christmas
（メリークリスマス）
以下のように言えます。
A： Merry Christmas to you and your family!
（あなたとご家族へ、メリークリスマス！）
B) Merry Christmas to you too !
（あなたにもメリークリスマス！）
参考になれば幸いです：-)
Merry Christmas is specifically used for the 25th of December which is popularly celebrated in Western countries. Happy Holidays can be used if you are unsure if the person celebrates Christmas or you won't see them before January 1st to wish them a Happy New Year's. I hope that this helps. :)
You can say "Merry Christmas."
You can also say "Merry Christmas and have a happy new year."
A : Merry Christmas!
B : Merry Christmas and have a happy new year!
"Merry Christmas."（メリークリスマス）と言えます。
また、
"Merry Christmas and have a happy new year."（メリークリスマス、良いお年を）
と言うこともできます。
A : Merry Christmas!
メリークリスマス！
B : Merry Christmas and have a happy new year!
メリークリスマス、そして良いお年を！
"I hope you have a blessed Christmas." expresses that you hope someone else's holiday is full of love, joy, and happiness. It has a warmer, more sincere meaning than simply saying "Merry Christmas." although saying "Merry Christmas." is perfectly acceptable. "Happy Holidays." can be used if you are unsure of whether or not the person celebrates Christmas, as there are many holidays celebrated around the same time.
"I hope you have a blessed Christmas."は、その人のクリスマスが愛と喜び、幸せにあふれたものになることを願うという意味です。"Merry Christmas"よりも暖かく誠実な言い方です。ただ、"Merry Christmas."でも全く問題ありません。
"Happy Holidays."は相手がクリスマスを祝うかどうか分からないときに使えます。これは、この時期にたくさんの祝日（holiday）があるからです。
Native speakers will say like this: “Merry Christmas”.
There are lots of other ways to say it, but this one is the most accurate and most commonly used.
You can also wish someone happy holidays, if you don't know whether they celebrate Christmas or not.
In English, we use the greeting, "Merry Christmas," during the holiday season (the month of December) to wish people a good Christmas. Nowadays, it is more politically correct to say, "Happy Holidays," however, because we don't know if the person celebrates Christmas. Saying, "Happy Holidays," includes all of the holidays in the month of December, so this is a more broad greeting. We also say, "Merry Christmas and a Happy New Year," to wish people a good Christmas and New Year.
英語ではホリデーシーズン（12月）の間には"Merry Christmas"（良いクリスマスを）というあいさつを使います。ただ、最近では"Happy Holidays"の方が差別的になりません、クリスマスを祝わない人たちもいるからです。"Happy Holidays"には12月の全ての祝日が含まれます、より意味の広いあいさつです。
また、"Merry Christmas and a Happy New Year"（メリークリスマス、そして良いお年を）とも言います。
Christmas time is celebrated in many countries around the world. If you want to greet someone at Christmas time you cna use any of these greetings.
1. Merry Christmas!
2. Happy Holidays!
3. Compliments of the season.
The last greeting is used in the month of December, not only on Christmas day.
クリスマスは世界中で祝われるお祭りですね。この時期に人と会ったときは、次のようにあいさつできます。
1. Merry Christmas!（メリークリスマス）
2. Happy Holidays!（ハッピーホリデー）
3. Compliments of the season.（季節のご挨拶を申し上げます）
三つ目の例は12月に使われるあいさつです、クリスマスに限りません。
We would use, "Marry Christmas!" to use as reference to the specific holiday of Christmas, whereas you can use, "Happy Holidays," to just refer to this holiday season in a much more general sense.
Well, if you would like to know a good greeting for Christmas, then the typical one would be 'Merry Chritmas'. It is quite often that seasonal cards will have a message such as the one exampled in the second sentence above. 'Christmas' is actually a holiday period in the UK, that starts before Christmas DAy and ends after New Year's day. So the second or third sentences may also be appropriate at this time of year.
Eg 'Seasons greetings to you all!'
クリスマスに使えるあいさつを知りたいということですね。これは一般的には 'Merry Chritmas' といいます。
二つ目の例はカードのメッセージとしてよく使われます。
イギリスでは、'Christmas' は12月25日前から元日後までの休暇期間を指します。ですから、二つ目・三つ目の例もこの時期に使うことができます。
例：
'Seasons greetings to you all!'（みんな、クリスマスおめでとう）
アメリカ合衆国 
イギリス 
南アフリカ 
カナダ 
オーストラリア 
