Thai and Lao are similar languages. Both Thai and Lao are part of the same family of languages: the Kra-Dai language family (as known as Tai-Kadai languages).
In their spoken form, Thai and Lao are to some extent mutually intelligible. Because Lao-speakers tend to consume some Thai media, they often can understand Thai better than Thai-speakers can understand Lao.
Approximately 80% of the vocabulary words in Thai and Lao have the same origin (these are what linguists call cognates).
Here are some examples of similar vocabulary words between Thai and Lao:
| Thai | Lao | English |
|---|---|---|
| ภาษา (phāsā) | ພາສາ (phāsā) | language |
| วัน (wan) | ວັນ (wan) | day |
| ข้าวเช้า (kâao-cháao) | ເຂົ້າເຊົ້າ (khao sao) | breakfast |
| ผัก (phak) | ຜັກ (phak) | vegetable |
| ห้อง (hɔ̂ng) | ຫ້ອງ (hong) | room |
| เตียง (teīyng) | ຕຽງ (tīang) | bed |
| ยินดี (yindī) | ຍິນດີ (nyindī) | happy |
| อ่าน (àan) | ອ່ານ (ān) | to read |
| เข้าใจ (kâo-jai) | ເຂົ້າໃຈ (khao chai) | to understand |
| เพลง (pleeng) | ເພງ (phēng) | song |
| ประตู (pratū) | ປະຕູ (pa tū) | door |
| คืน (khụ̄n) | ຄືນ (khūn) | night |
| ได้ยิน (dâiyin) | ໄດ້ຍິນ (dainyin) | to hear |
| ป่า (bpàa) | ປ່າ (pā) | forest |
| พ่อ (pɔ̂ɔ) | ພໍ່ (phǭ) | father |
| สุด (sùt) | ສຸດ (sut) | to end |
| ต้นไม้ (dtôn-máai) | ຕົ້ນໄມ້ (tonmai) | tree |
| เลือก (leụ̄xk) | ເລືອກ (lư̄ak) | to choose |
| รัก (rák) | ຮັກ (hak) | to love |
| ขอบใจ (kɔ̀ɔp-jai) | ຂອບໃຈ (khǭp chai) | to thank |
| เห็น (hěn) | ເຫັນ (hen) | to see |
| เล่า (lèā) | ເລົ່າ (leoa) | to tell |
| ไป (bpai) | ໄປ (pai) | to go |
| เปิด (peid) | ເປີດ (poed) | to open |
| ชนะ (chá-ná) | ຊະນະ (sana) | to win |
| ชายแดน (chāydæn) | ຊາຍແດນ (sāi dǣn) | border |
It is easy to visually differentiate between the Thai and the Lao scripts: The Lao script uses more curved lines than the Thai script.
In Thai and in Lao, the individual words are not separated by spaces. This is one of the things which makes learning these languages more difficult.
Both the writing systems for Thai and for Lao are alphasyllabaries. The main symbols are the consonants whereas the vowels consist in additional markets which are added above, below or on the side of the consonant symbols.
The Thai script has 44 consonants, which is significantly more than the 27 consonants in the Lao script.
There are some duplicate consonants in the Thai script (consonants which correspond to the same sound). The reason is that the Thai script was designed to accommodate the many loanwords from Sanskrit and Pali which are in the Thai language.
Over the centuries, some of the pronunciation nuances which exist in the original Pali and Sanskrit words have disappeared from the way these words are pronounced in the Thai language. Today these duplicate consonants indicate the etymology of the words rather than serving to distinguish nuances in pronunciation.
The Lao language underwent some spelling reforms in order to simplify the spelling of its Sanskrit and Pali loanwords, thereby making the written language closer to the way it is spoken. In the process, duplicate consonants were removed from the Lao language.
In Thai and Lao there are many loanwords from Sanskrit and Pali. This is similar to how English has loanwords from Latin and Greek. (see this comparison of Thai and Sanskrit)
Theravada Buddhism is the most common religion in both Thailand and Laos. The Pali language (which originates from Sanskrit) is the language of the Pali Canon which are the texts of Theravada Buddhism. This explains why there are so many Pali loanwords in Thai and Sanskrit.
English-speakers use the same pronouns regardless of who they are talking to. In contrast, Thai and Lao are languages which have a variety of pronouns depending on the level of formality and the social relationship between the speakers.
In English, verb endings change depending on the subject pronoun and the tense. Thai and Lao are languages in which the verb endings stay the same regardless of the subject pronoun and the tense.
In Thai and Lao, the tense of a verb is indicated by adding extra words such as time reference words.
Thai and Lao are languages which can be difficult for English-speakers to pronounce correctly. The reason is that these are languages which have tones.
The Thai language has 5 tones (high, mid, low, falling and rising), whereas Lao has 6 tones (it distinguishes between high falling and low falling). Although some of the dialects of Lao only have 5 tones.
In Languages like Thai and Lao, a particle is added at the end of a sentence to make the sentence more polite.
Two of the most common sentence-ending particles in Thai are « ครับ » (kráp) which is used by male speakers, and « ค่ะ » (kâ) which is used by female speakers.
The Isan language, which is spoken in northeastern Thailand is a descendent of the Lao language. In addition to being the name of this language, the word Isan is also the name of a region in the northeastern part of Thailand. The term itself comes from the Sanskrit word « ईशान्य » (īśānya) which means “north-east”.