Scots is a product of the mixture of several different languages, and not only Germanic. Picts, a non-Indo-European nation, lived here in prehistoric times, but then Romans from England and Gaels from Ireland pushed them north and settled here in Scotland. Then in the 5th century AD Angles coming from Germany and Denmark established several kingdoms in this region and slowly repelled Celtic and aboriginal population to the Highlands. But certainly, Germanic colonists acquired many words and place names from Celtic and maybe even Pictish language. The 9th language was the beginning of severe Viking intrusions into Scotland. They settled here, mixing with Anglian population and creating an ethnic term Scots. The language, therefore, had quite a different history from English.
Different is also the structure of it in some aspects. The phonetics avoided the Great Shift of Vowels in English, and still uses many sounds which were lost by Middle English like pure Indo-European [a], [u], [o]. Diphthongs are quite numerous, including such as oa, ou, ey etc., and some of them do not have correspondent sounds in English, e.g. ui, pronounced like German ö. Consonant are also sometimes different from English, like ch which sounds like in Scottish Gaelic. The system of nouns and verbs is similar to English, except for the spelling of some forms. The Past tense is marked with the ending -t / -it, Infinitive has a particle ti. There are four grades of demonstrative pronouns, while English uses just two:
singular this lad tha
lad thon lad yon lad
plural thir lads thae lads thon lads yon lads
The two last ones demonstrate things more distant than "that".