Assessment of Student's Learning: Explanatory Context

Assessment of student learning may be formative or summative.

Assessment, especially if it is summative, is usually graded.

Achievement of satisfactory summative grades is frequently used to signify progress or the achievement of an award. (The award of a Ph.D., for example, is a situation where summative grading is rarely used.)

Assessment covers the whole development of student learning evaluation, while grading refers to the specific attachment of marks/grades. The UK QAA (2000) notes:

Assessment plays a significant role in the learning experience of students. It determines their progression through their programmes and enables them to demonstrate that they have achieved the intended learning outcomes. It is assessment that provides the main basis for public recognition of achievement, through the awarding of qualifications and/or credit.

Assessment is usually construed as being either diagnostic, formative or summative. … Any assessment instrument can, and often does, involve more than one of these elements. So, for example, much coursework is formative in that it provides an opportunity for students to be given feedback on their level of attainment, but also often counts towards the credit being accumulated for a summative statement of achievement. An end-of-module or end-of-programme examination is designed primarily to result in a summative judgement on the level of attainment the student has reached. Both formative and summative assessment can have a diagnostic function. Assessment primarily aimed at diagnosis is intrinsically formative, though it might, rarely, contribute towards a summative judgement.

It is important to distinguish between assessment of student learning as described here and the USA notion of assessment as part of the Assessment Movement, which is more akin to improvement of the student experience.

Reference: 

http://www.qualityresearchinternational.com/glossary/assessmentoflearning.htm