English and Scots are very similar. The two languages are both Germanic and Scots has Anglo-Saxon roots. You can compare them here-
English-
http://en.wikipedia.org/wiki/Scots_language
Scots-
http://sco.wikipedia.org/wiki/Scots_leid
I think you are confusing Scots with Scottish Gaelic, which is spoken in the Highlands and the Hebrides and has its roots way back to the Celtic languages spoken in the British Isles before the Roman conquest of England and Wales. Scots is spoken in the Lowlands of Scotland, south of the Caledonian Canal.
I may be wrong, but I get the impression that you think Gaelic is just one language and that Celtic is another name for it. There is no one language such as Celtic. There are Celtic languages that form the Celtic language family such as Cornish, Welsh, Manx, Breton, and Irish Gaelic. Scottish Gaelic is also one of them, but Scots is not, as explained in the above paragraph. The Celtic languages are markedly different from each other, even though they are from the same language family, as you can see from below.
Examples
Article 1 of the Universal Declaration of Human Rights:
All human beings are born free and equal in dignity and rights. They are endowed with reason and conscience and should act towards one another in a spirit of brotherhood.
Scottish Gaelic: Tha gach uile dhuine air a bhreth saor agus co-ionnan ann an urram 's ann an còirichean. Tha iad air am breth le reusan is le cogais agus mar sin bu chòir dhaibh a bhith beò nam measg fhein ann an spiorad bràthaireil.
Irish: Saolaítear na daoine uile saor agus comhionann ina ndínit agus ina gcearta. Tá bua an réasúin agus an choinsiasa acu agus dlíd iad féin d'iompar de mheon bráithreachais i leith a chéile.
Manx: Ta dagh ooilley pheiagh ruggit seyr as corrym ayns ard-cheim as kiartyn. Ren Jee feoiltaghey resoon as cooinsheanse orroo as by chair daue ymmyrkey ry cheilley myr braaraghyn.
Welsh: Genir pawb yn rhydd ac yn gydradd â'i gilydd mewn urddas a hawliau. Fe'u cynysgaeddir â rheswm a chydwybod, a dylai pawb ymddwyn y naill at y llall mewn ysbryd cymodlon.
Cornish: Pub den oll yw genys frank ha kehaval yn dynita ha gwiryow. Yth yns i enduys gans reson ha cowses hag y tal dhedhans gwul dhe udn orth y gila yn spyrys a vredereth.
Breton: Dieub ha par en o dellezegezh hag o gwirioù eo ganet an holl dud. Poell ha skiant zo dezho ha dleout a reont bevañ an eil gant egile en ur spered a genvreudeuriezh.
http://en.wikipedia.org/wiki/Celtic_languages
Also, Scottish Gaelic is pronounced as 'GA-LICK' whilst Irish Gaelic is pronounced as 'GAY-LICK'.