- 1. no dual endings. Instead, one uses paraphrases such as etad pustakadvayam atirucikāram.
- 2. no past endings beside ppp. Instead, one uses the sma paraphrase, e.g., sadānandamahodayaḥ māṃ saṃskṛtasambhāṣaṇam adhyāpayati sma.
- 3. (almost) no second person ending. Instead, one addresses people with bhavān/bhavatī + III person ending.
- 4. shorter compounds (as obvious, in a spoken language).
- 5. hardly any sandhi at all.
As for vocabulary, all the everyday vocabulary is either made up (vidyutpatra for email), imported (seba or sebaphala for apple) or re-adapted (vimāna for airplane). One will not need it in one's Classical Studies.
However, in many Spoken Sanskrit classes one reads many subhāṣitas, and hence gets a chance to learn some metrics and get in touch also with classical Sanskrit.
Most important, one has to figure out which style of learning suits oneself most: do you remember things because you heard them or because you read them? If the former, the course will terribly enhance your understanding of Sanskrit. You will start reading texts autonomously, instead of having to look for every single word on the dictionary. If you keep on working on it, the ultimate result is to start questioning texts in Sanskrit. And Sanskrit texts tend to reveal more to the one who questions them in the appropriate way;-)