http://www.examiner.com/article/comparing-eld-and-sdaie
Even experienced teachers get confused about the differences between ELD (English Language Development) and SDAIE (Specially Designed Academic Instruction in English). This confusion comes, at least in part, because both focus on providing comprehensible education for ELLs.
In addition, most mainstream teachers are not accustomed to dealing with language, other than content specific vocabulary.. ELD is the teaching of English to speakers of another language(s) and SDAIE is the teaching of content knowledge, skills and language in a way that ELLs can understand and work with the content.
SDAIE is the primary methodology used by mainstream teachers. Their expertise and knowledge in a specific field of study allows them to have the flexibility to develop ways to concretize their lessons in ways which makes them comprehensible to ELLs. The grade-level content standards and curriculum is the focus of the classes.
Good teachers use SDAIE strategies consistently in their teaching. SDAIE for ELLs differs from "good teaching" because it requires knowledge of how language develops so accommodation of lessons and assessments is made for the different ELD levels - beginner, early intermediate, intermediate, early advanced and advanced.
ELD works on developing language ability and knowledge. For example the consistent and correct use of: past tense, the difference between present tense and present progressive (eat vs. is eating), simple past from past perfect (slept vs has slept), etc. Making complex and compound sentences ("He slept soundly and frequently." vs "While he was sleeping he had a dream."); the ability to write a paragraph, appropriately, punctuating writing correctly, understanding the writing style used in English (linear); being able to read and understand textbooks, etc. for knowledge and learning; being able to understand and use vocabulary that is used across the curriculum such as "investigate," "summarize," "analyze," etc. These skills are not content specific and are necessary to succeed in school and life.
The overlap between the two methodologies contributes to the confusion. Both work on the development of academic language - content specific and cross curricular vocabulary and language and accommodating lessons and assessments. They use the same strategies. ELD focuses on language development usually using content areas for language development.
Moreover the content is not at grade level and the language is more important. SDAIE teaches grade-level content and is aware of language development, teaching content vocabulary and language as well as reading and writing in mini-lessons or scaffolding. Grade-level curriculum and standards are the focus.